Thermo Finnigan ELEMENT2 Operating Manual

ELEMENT2

ELEMENT2 Operating Manual

Part No.: 1091281

ELEMENT2 Operator Manual - Rev. 2 - Issue 08/2001

Section 1 - Structure of the Manual

Page 2 of 5 ELEMENT2 Operator Manual - Rev. 2 - Issue 08/2001


1 9 Structure of the Manual 2 Overview / Warnings and Safety

3 Basics 1 - Designing Analyses

4 Basics 2 - Introduction to the ELEMENT2

5 Basics 3 - Windows NT 4.0

6 Installation of the ELEMENT2 Software

7 Starting the ELEMENT2

8 Tuning the ELEMENT2

9 The Mass Calibration

10 Creating Methods

11 The Standard Editor

12 Creating Sequences

13 Showing the Data

14 Results the Report Generator



1 The Program Group ELEMENT software package Release 2.0

Icon Application see Section Paragraph

Installer Section 6

Executive Section 7 (7.3)

Instrument Section 7 (7.4)

Tune Section 8

Mass Calibration Section 9

Method Editor Section 10

Standard Editor Section 11

Sequence Editor Section 12

Show Section 13

Results Generator Section 14


Section 1 - Structure of the Manual Technical information contained in this publication is for reference purposes only and is subject to change without notice. Every effort has been made to supply complete and accurate information; however, Thermo Finnigan assumes no responsibility and will not be liable for any errors, omissions, damage, or loss that might result from any use of this manual or the information contained therein (even if this information is properly followed and problems still arise). This publication is not part of the Agreement of Sale between Thermo Finnigan and the purchaser of an ELEMENT system. In the event of any conflict between the provisions of this document and those contained in Thermo Finnigan's Terms and Conditions, the provisions of the Terms and Conditions shall govern. Reference to System Configurations and Specifications supersede all previous information and are subject to revision without notice.

1.1 Worldwide represented by

Australia, Thermo Finnigan Australia Pty.Ltd., Unit 14, 38-46 South Street, Rydalmere, N.S.W 2116 +61 2-9898 9000

Belgium, Thermo Finnigan BVBA., Groenenborgerlaan 84, 2610 Wilrijk, Antwerpen +32 3-8250 670

France, Thermo Finnigan France SA, Hightec Sud, 12. Anenue des Tropiques, ZA de Courtaboeuf - BP 141, 91944 Les ULIS Cedex +33 1-6918 8810

Germany, Thermo Finnigan GmbH, Boschring 12, 63329 Egelsbach +49 6103-408 0

Italy, Thermo Finnigan APG Italy, Strada Rivoltana KM 4, 20090 Rodano (MI) +39 02-95059 1

Japan, ThermoQuest K.K., Nishi-Shinjuku Toyokuni Bldg., 2-5-8 Hatsudai Shibuya-Ku, Tokyo 151-0061 +81 3-3372 3001

The Netherlands, Thermo Finnigan BV, Druivenstraat 33, 4816 KB Breda +31 76-5878 722

People's Republic Thermo Finnigan Beijing Rep. Office, Ping An Mansion, No. 23, Finance Street, Beijing 100032 of China, +86 10-66210 839 - 846

Spain, Thermo Finnigan S.A., Avenida de Valdelaparra 27, Edificio Alcor, Planta 2, 28108 Alcobendas (Madrid) +34 91-6574 930

Sweden, Thermo Finnigan AB, Pyramidbacken 3, 14175 Kungens Kurva +46 8-5564 6800

United Kingdom, Thermo Finnigan UK, Paradise, Hemel Hempstead, Herts HP2 4TG +44 1442-233 555

U.S.A., Thermo Finnigan LLC, 55 River Oaks Parkway, San Jose, CA 95134-1991 3 +1 408-433 6800 In countries not contained in the above list renowned instrument distributors represent Thermo Finnigan. Information and specifications herein are subject to revision without prior notice. The availability of components and options is subject to verification by local representatives. MANUAL HISTORY February 1999 Rev. 0 Issue 02/99 January 2000 Rev. 1 Issue 01/00 For additional information please check our Home page: http://www.ThermoFinniganMAT.de Thermo Finnigan MAT GmbH is a Thermo Electron business. Copyright 2000/2001 by Thermo Finnigan MAT GmbH. All rights reserved. Printed in Germany



ELEMENT2

Operator Manual Section 2 - Overview / Warnings and Safety

P/N 1091281

Section 2 - Overview / Warnings and Safety




1 Structure of the Manual

2 Overview / Warnings and Safety




6 Installation of the ELEMENT2




10 Creating Methods



13 Showing the Data




Table of Content

2. OVERVIEW / WARNINGS AND SAFETY CONSIDERATIONS ........................5

2.1. One word before..............................................................................................................5 2.2. Global Overview ..............................................................................................................5

2.2.1. Configuration of the Instrument...................................................................................6 2.3. The ELEMENT Manuals...................................................................................................7 2.4. Customer Training ..........................................................................................................8 2.5. Service and Maintenance................................................................................................9 2.6. Installation of the System .............................................................................................10 2.7. Safety Considerations...................................................................................................10

2.7.1. The symbols used in this manual ..............................................................................11 2.7.2. Warnings..................................................................................................................11 2.7.3. Cautions ...................................................................................................................13

2.8. Repair of contaminated parts .......................................................................................15

Table of Figures Figure 1 Front side of the ELEMENT2 6



2. Overview / Warnings and Safety Considerations

2.1. One word before The software suite for the ELEMENT consists of several applications. In order to deliver the results the customer expects, all applications have to work together. E.g. some of the applications help to define what kind of data are needed, some applications collect data which others modules evaluate. A report generator is included as well. The hardware interface is an Ethernet connection that links the computer in front of you to an intelligent interface inside the Mass Spectrometer. This interface is called the Front-End Computer. It controls the hardware, monitors the status of most hardware components and delivers the data. An integrated part of the software pack is the Diagnostic tool. It allows direct access to almost every setting and value of the hardware. The diagnostic supersedes all instrumental settings from other ELEMENT applications. Additionally, closing the diagnostic window resets the instrument settings to that status as it was observed when the diagnostic window was opened (regardless of any changes made since). This, of course, can be painful in case the diagnostic was opened during the run of a script or procedure (e.g. Starting the Plasma).

WARNING Therefore, be extremely careful with the diagnostic.

2.2. Global Overview This chapter provides a very brief overview of the ELEMENT ICP-MS system and a somewhat more detailed synopsis of the ELEMENT manuals, in particular the 'ELEMENT Operating Manual'. It also discusses general items such as service, maintenance, training, etc.. Warnings, Cautions and Notes are discussed in paragraph 2.7. The ELEMENT ICP-MS is an Inductively Coupled Plasma (ICP) sector type mass spectrometer. It has been designed for multi-element analysis. The combination of high sensitivity and very low background noise makes it particularly suitable for elemental trace and ultratrace analysis. The design principle is a double focusing sector field analyzer based on a reverse Nier-Johnson geometry (i.e. the magnetic field is located in front of the toroidal electric field). this geometry provides an optimum abundance sensitivity. The analyzer works with 8 kV accelerating voltage.



2.2.1. Configuration of the Instrument The major sections of the ELEMENT2 are: the Inlet section on the right hand side, the Electronics cabinet on the left hand side, the Analyzer section in the upper middle area, and the support section below the analyzer.

Figure 1 Front side of the ELEMENT2

Inlet section The Inlet section on the right hand side contains:

the load coil, mounted on top the matching unit, the torch with gas connections Guard electrode, the peristaltic pump, and the electronics for automated X / Y / Z adjustment of the torch & load

coil. The inlet section is mounted on a sturdy hinge and can be opened for easy access to all inlet parts.

Electronics Cabinet The Electronics cabinet on the left hand side of the ELEMENT2 contains

all electronic boards for the Analyzer, all interface boards except the preamplifier, the Front end computer with the Ethernet connection.

Support section The main parts of the support section below the Analyzer section are

the RF generator , the electronics for the turbo pumps, the mechanical pumps, and the distribution units for power, gas and cooling water.

ELEMENT2

REFLECTED POWER

FORWARD POWERG - SYSTEM READY

Y - STANDBYPUMP SYSTEM

OFF

ON

HV < 10 mbar

FV < 10 mbar

TP A > 50%

TP B > 50%TP C > 50%

TP D > 50%

INTERFACE PUMP

FORE PUMP (TP)

SKIMMER VALVE

-4

-1

RFON / OFF

FRONT END PC

RESET

TOPRCH IN POS.

ARGON PRESSURE

COOL GAS FLOW

COIL COOLING

INTERFACE COOL.

HV ELECTRONICS

INTERLOCK HOOD

BOARD CHECK

Inlet section Analyzer Section

Electronics Cabinet

Operating Panel and Status Display

Support Section



Analyzer section The analyzer section contains the mass spectrometer:

The plasma interface, the transfer optics with the entrance slit, the magnetic sector, the electric sector (ESA) with the exit slit, the secondary electron multiplier (SEM), and the Preamplifier. All analyzer components are mounted on a warp resistant optical bench which is protected against possible vibration by shock absorbers. The analyzer area is covered by doors (can be lifted up and folded) and temperature controlled to ensure the highest possible mass stability.

The Vacuum In order to maintain the vacuum inside the analyzer, four turbo pumps are attached to the analyzer. A small 5l/min fore pump supports the turbo pumps. A second fore pump (30 l/min) is attached to the plasma interface as a first pumping stage.

The Computer In the data system in front of the operator runs the ELEMENT software on the Microsoft Windows NT platform. Please note, the software will NOT run with other operating systems.

2.3. The ELEMENT Manuals Modern mass spectrometry is a broad field incorporating a large number of different instrumentation and application techniques. A general introduction to mass spectrometry is beyond the scope of the ELEMENT manuals. They are therefore restricted to descriptions of the function and the fundamental operation of the ELEMENT system. Two types of manuals are available: the manuals from Finnigan MAT, and the manuals and handbooks provided by the suppliers of ELEMENT

components, e.g. for pumps, pressure gauges, RF Generator etc..

The manuals from Finnigan MAT for the ELEMENT2 are: the ELEMENT2 Operating Manual (this manual), the ELEMENT2 Hardware Manual, and the ELEMENT2 Pre-Installation Requirements. This document is the Operating Manual. It describes the ELEMENT software, how to start the instrument, the basics of analyses planning, executing analyses, presenting analysis results etc. (see page 2 of this manual). The Hardware Manual describes the hardware components of the system and gives advice on service and maintenance.



The Pre-installation Requirements is a INFO-guide and contains information about the site preparation for the Instrument. This guide is very useful during the planning phase of the laboratory. Therefore, the Pre-installation Requirements has been mailed together with the order acknowledgment. However, additional copies of the Pre-installation Requirements can be ordered from your Finnigan representative or downloaded from our Web Page: . All other manuals are delivered with the instrument. In case a of a changed or new hardware, the manuals supplied with the instrument will reflect the change.

2.4. Customer Training Operator Training Thermo Finnigan MAT provides training courses for customers. The key-

points of these courses are system handling, applications and optimization of the system. The courses are held in either German or English.

Service Training Special courses are held for Thermo Finnigan MAT Field engineers and

engineers of companies and dealers associated with Thermo Finnigan MAT. The key-points of these courses are maintenance and service, system installation and the initial start-up operation. On request, qualified engineers from customer sites may also participate in these courses.

CAUTION Thermo Finnigan MAT and Finnigan MAT points out that mere

participation in a training course does not automatically authorize the user to carry out service at the instrument during the warranty period. Thermo Finnigan MAT and Finnigan MAT will not be liable for personal injury, damage to the instrument or damage of a general nature arising from service work carried out by the customer. Like in all mass spectrometers, potentially lethal voltages are applied to certain parts. In the region of the Inlet system, dangerous radiation and hazardous gases are generated. Thermo Finnigan MAT emphasizes that the safety devices must not be removed or altered!

Operators It is worthwhile to have one key operator who is responsible for the

instrument. This will help to get the maximum benefit from this high technology equipment. This key operator should additionally be responsible for the contact between the customers laboratory and the Thermo Finnigan MAT Support Group / Finnigan Application Laboratory.

Training Finnigan MAT recommends that the key operator undertakes the training Recommendations course at Thermo Finnigan MAT about one month after the system has

been installed. Afterwards the key operator may train further operators, and may create special operating instructions for his laboratory. Of course, additional operators of the customer may also undertake the Thermo Finnigan MAT training courses.



Training Course Information about the dates, contents and fees of the training courses

are Information available from either from your local Thermo Finnigan MAT office or the

following address:

Mrs. Susanne Tobin Thermo Finnigan MAT GmbH

Barkhausenstr. 2 D-28197 Bremen, Germany Phone: ++421-5493 325 Fax: ++421-5493 426 e-mail: [email protected]

You can also check our WebPage:

2.5. Service and Maintenance

Maintenance In order to secure optimum system performance, the user must perform routine preventive maintenance. Maintenance intervals and procedures are described in the Hardware Manual and especially in the Manuals provided by the supplier of the particular part (e.g. Pumps).

Preventive maintenance must commence with installation, and must be carried out during the warranty period in order to maintain the warranty. Thermo Finnigan MAT offers routine maintenance and service contracts. Please contact your local Thermo Finnigan MAT office for more information.

Service The ELEMENT2 system contains complex and expensive components.

Certain components are at high voltages! Due to safety devices it is not possible to activate the plasma while the covers are removed!

The plasma transmits all kind of radiation including a very intense light with strong IR and UV components! If service is necessary, please call your local dealer or the local Thermo Finnigan MAT support group. While calling the service, please try to describe your observation as good as possible. A precise description of the fault will facilitate repair and reduce the costs!

WARNING Ensure that during maintenance work the power switch for the electronics

(on the front of the Electronics Mains Distributor rack (front of the mass spectrometer)) is OFF (position 0)! Note that particular danger arises if safety circuits (e.g. micro switches) are disconnected or altered.

We do not recommend that customers do service work at the electronics. Many parts of the system are at high voltages! Do not remove the protective covers from cables, boards, electronic units and other parts! Do not touch parts at high voltage!

Spare Parts Spare parts are listed with their part numbers in appendix A of the

Hardware Manual. Please use the part names and the part numbers when ordering. Original Finnigan and Thermo Finnigan MAT spare parts have been carefully selected and tested. It is therefore beneficial to use only genuine Finnigan MAT spare parts! The use of parts from other sources may invalidate the warranty!



Repair of Parts Parts contaminated with radioactive materials must not be returned to

Finnigan MAT or Thermo Finnigan MAT - either under warranty or the parts exchange program! With your signature you certify that the returned parts have been decontaminated and / or are free from hazardous materials! We hope you will understand the need for this safety precaution. Please use the completed and signed Repair-Covering Letter when returning parts to the factory for repair. Repair-Covering Letters can be found at the back of the Hardware Manual. Please describe the defect of the returned part as much detailed as possible.

Service Calls For information concerning service, please contact your local Thermo Finnigan MAT office or, in Germany, the following address: Finnigan MAT GmbH, Bremen Telephone: (49) 421 5493 385 ICP Mass Spectrometry Fax: (49) 421 5493 396 Barkhausenstr. 2 D 28 197 Bremen GERMANY

2.6. Installation of the System A Finnigan field engineer will perform the installation of the ELEMENT2. He will demonstrate the system specifications and the fundamentals of the equipment, the basic operation and routine maintenance. In order to provide a maximum of information transfer, the operator should be present during the entire installation period.

2.7. Safety Considerations All Sector field ICP mass spectrometers contain possible sources of danger: High voltages are applied to many parts, boards and cables; the plasma torch operates at a dangerous high RF-voltage; the plasma emits a wide range of dangerous radiation including

strong components of ultraviolet (UV) and infrared (IR); the plasma temperature is at > 8.000 K; the exhaust gases from the torch enclosure can be toxic; during in operation, parts of the torch box become every hot; the exhaust gases from the vacuum pumps may contain toxic

components; when analyzing hazardous samples or using hazardous sample

additives, parts of the nebulizer, the torch, the analyzer and the vacuum pumps can be contaminated and must be decontaminated before service and repair.

The operator must be familiar with the handling and disposal of hazardous (i.e. toxic, carcinogenic, or corrosive / irritant) chemical compounds and with national and international regulations governing this subject.



Precautionary measures have been incorporated into the ELEMENT2 Mass Spectrometer in order to prevent injury to the operator and damage to the instrument. All potentially dangerous areas (high voltage, high temperature, radiation, etc.) are shielded or covered during normal operation. However, it may be necessary to remove protective devices in order to carry out service and maintenance! Call the Thermo Finnigan MAT Support Dept. if service or maintenance is required. The service and maintenance, which must be undertaken by the user, is limited and described in detail in the ELEMENT2 Hardware Manual. If not fully trained of servicing the system, do not carry out any service or maintenance while the power is switched ON! Do not modify or alter protective covers, and do not ignore safety precautions! Note that the Finnigan ELEMENT manuals contain the necessary information concerning dangers - read these manuals carefully and ensure that attention is paid to all Warnings and Cautions!

2.7.1. The symbols used in this manual The following symbols are used throughout this manual and the ELEMENT Hardware Manual MS:

Note Notes contain information on issues that affect the quality of your data.

Notes can also contain hints, and may refer you to another document.

WARNING A 'Warning' calls attention to a condition or possible situation that could cause injury to the user.

CAUTION A 'CAUTION' calls attention to a condition or possible situation that could

damage or destroy the product or the user's work.

2.7.2. Warnings Warnings call attention to conditions or situations that could cause injury to the user. In the Hardware Manual, Warnings come along with the description of the system and its components, and with the description of service and maintenance operations. Warnings are given where danger may arise when the instrument is handled inadequate. The major Warnings are summarized below.

High Voltages and RF Ignition of the torch is realized by electric sparks at very high voltages

while a dangerous RF-voltage is applied to the tip of the torch by the load coil. As a safety measure, ignition is possible only when the torch has been installed correctly and the torch box is closed and locked!

WARNING Please do not modify or alter the safety measures.



During normal operation, the Flight Tube, flanges and parts of the Analyzer and the ESA are at a high voltage! Some of the circuit boards and cables float at high voltages as well. Those high voltages are switched off by a safety device when opening the analyzer cabinet (folding doors).

Note In order to avoid empty data sets, please do not open the analyzer cabinet during analysis.

WARNING Switch off the power before touching components! Note that even if the main power has been switched off, some of the components - such as capacitors - may still contain dangerously high voltages! Ensure that during maintenance work the main power switch for the electronics on the Electronics Mains Distributor (front of the mass spectrometer) is turned into the OFF (position 0)! Note that particular danger arises if safety circuits (e.g. micro switches) are disconnected or altered. Finnigan does not recommend to perform service work by the user. Many parts of the system are at high voltages! Do not remove or alter the protective covers from cables, boards, electronic units and other parts!

Hazardous Exhaust Gases. Do not operate the ELEMENT mass spectrometer if it is not connected to

an efficient external exhaust system! In the plasma, ozone and sample elements are produced! In addition, hazardous vapors and gases may be expelled by the forepumps! It is extremely dangerous to release these exhaust gases into the laboratory!

WARNING If the laboratory exhaust system is controlled separately, ensure that it is working correctly when the mass spectrometer is in operation! The Exhaust Filter in the common outlet line of the forepumps does not clean the exhaust gases - this filter can remove the oil vapors from exhaust only!

High Temperatures

Individual parts of the Plasma Torch are very hot, and remain hot for a long time after the Plasma has been switched off! Let them cool down before touching them, otherwise there will be a risk of burns!

Radiation from the plasma The protective glass on the Torch Box must not be removed. The emission of the plasma is very intense and contains high levels of ultraviolet and infrared light. Removal of the protective glass may cause injury to the eyes!

Broken Glass ware Too high pressure of the cooling water may cause the glass spray chamber to burst, and the resulting broken glass could cause injury or damage. The maximum permissible water pressure is 1.2 bar.



The Use and the Handling of Gases

Pay attention to your own national, and the international safety regulations when storing and transporting pressurized containers e.g. gas cylinders! Ensure that containers and lines are gas-tight when in storage and in operation. Note that Argon gas is heavier than air! Argon will decrease the oxygen concentration in the air, presenting a danger of suffocation! Symptoms of a lack of oxygen are drowsiness, difficulty in breathing and increased blood pressure. Inhalation of pure Argon leads immediately to unconsciousness and suffocation!

Contamination Parts of the inlet system (nebulizer, torch, cones, apertures, lenses, slits,

detector, etc.) may become contaminated with hazardous materials. WARNING Avoid to touch these parts without protection! The use of gloves is highly

recommended. Contaminated parts must either be decontaminated, or disposed in

accordance with your local regulations! Hazardous compounds introduced into the analyzer system may dissolve in the pump oil. Accordingly, use only locally approved containers and procedures for disposing the waste oil. Note, that contaminated pumps must be emptied and decontaminated before they are returned to Finnigan MAT for repair or exchange!

Spilled Water When working on the water cooling system, ensure that all hose

connections and unions are correctly tightened, otherwise leaking cooling WARNING water may cause damage! Be extremely careful to avoid leaks when

exchanging a defective Load Coil! If leaks arise in the torch region, the leaking water could enter the electronics of the RF - generator and lead to damage and short circuits!

Handling of Chemicals

WARNING It is not the purpose of this manual to give advice on the handling of

chemical compounds - we refer the user to the relevant literature. However, the storage, handling, and introduction of hazardous (i.e. toxic, carcinogenic, mutagenic, or corrosive/irritant) chemicals; the handling and decontamination of contaminated parts; and the disposal of hazardous waste must be carefully carried out in accordance with your local regulations!

2.7.3. Cautions

Cautions call attention to conditions or possible situations that could damage or destroy the ELEMENT System or the user's work. Cautions are to be found in the relevant sections of the text. The most important Cautions are summarized below.



Normal Operation and Service The system should only be operated by trained personnel. Read the

manuals before starting the system, and ensure that you are familiar with all Warnings and Cautions cited in the manuals!

CAUTION Thermo Finnigan MAT an Finnigan MAT points out that mere participation in a training course does not authorize the user to carry out service at the instrument during the warranty period. Finnigan MAT and Thermo Finnigan MAT will not be liable for personal injury, damage to the instrument or damage of a general nature arising from repairs which have been carried out by the customer.

Like in all Mass Spectrometer, potentially lethal voltages are applied to certain parts; in the region of the torch, dangerous radiation and hazardous gases are generated. We emphasizes that no covers must be removed, and that the safety devices must not be altered! Spare parts are listed in the spare parts lists of the ELEMENT Hardware Manual. Please use the part names and the Finnigan MAT part numbers when ordering. Note that Finnigan MAT spare parts have been carefully selected and tested. It is therefore advisable to use only genuine Finnigan MAT spare parts! The use of parts from other sources may invalidate the guarantee.

Vacuum System CAUTION Do not vent the system via the Skimmer Gate Valve!

Do not open the Skimmer Gate Valve when the fore vacuum pump of the first stage is switched off! This will cause the system to vent immediately!

Do not touch internal parts with bare hands! Use lint-free gloves to avoid contamination which would increase the analytical background!

Please take care that no parts (e.g. screws) drop into the system.

Cooling Water The flow rate of the water circulation should be 7.5 l/min @ 6 bar. The inlet temperature should be in the range of 15 C and 17 C (59 F to 63 F). Thermo Finnigan MAT's recommendation regarding the water quality of the closed-loop cooling systems used with the ELEMENT ICP-MS is: Conductivity: 1MOhm Water) Solid residual: 50 m.

CAUTION If the water becomes conductive due to contamination, the lifetime of your matchbox goes down to zero within minutes. Hint: the most common source of contamination results from dissolvation of the water fittings (brass).



Argon Gas Pressure

The settings of the build in pressure regulators must not be changed. Nevertheless, if it becomes necessary to readjust the settings, call the Thermo Finnigan MAT Support Group!

Magnet Do not try to move the magnet the position is optimized for maximum performance of your system. Beside this, the movement could damage the insulating foils between the magnet poles (on ground level) and the flight tube (on high voltage). Nevertheless, if it becomes necessary to move the magnet, call the Thermo Finnigan MAT Support Group!

RF shielding CAUTION Handle all RF shields in the vicinity of the plasma interface with care!

The shielding is mandatory for safety and should not be damaged or warped!

Torch and Nebulizer

Handle the glass (quartz) parts with care - they are very delicate, may break easily and they are expensive!

2.8. Repair of contaminated parts

Analyses of hazardous materials (samples) may contaminate certain parts of the system! In order to protect your and our employees, we ask you to observe some special precautions when returning parts to the factory for exchange or repair.

Contamination Where mass spectrometer parts have been contaminated with hazardous materials, Thermo Finnigan MAT can only accept these parts for repair if they have been properly decontaminated prior to their return. Materials that, because of their structure and their applied concentrations, may be toxic, or which, in publications, are reported to be toxic, are regarded as hazardous. Materials that generate synergetic hazardous effects when combined with other materials present are also included in the category of hazardous materials.

Repair-Covering You need to sign the Repair-Covering Letter, certifying that the returned Letter parts have been decontaminated and are free from hazardous materials.

Two Repair-Covering Letters are included at the end of the Hardware Manual. Copies are available at the Thermo Finnigan MAT Support Group.

Radioisotopes Parts contaminated with radioactive materials must not be returned to

Thermo Finnigan MAT - either under warranty or the part exchange program!

Service Engineers If parts of the system could possibly be contaminated with hazardous materials, please ensure that the service engineer is informed before he starts working on the system!


ELEMENT2

Operator Manual Section 3 Basics 1 - Designing Analyses

P/N 1091281

Section 3 Basics 1 - Designing Analyses




1 Structure of the Manual

2 Overview / Warnings and Safety




6 Installation of the ELEMENT2 Software




10 Creating Methods



13 Showing the Data




Table of Contents

3 Designing an Analysis 5

3.1 Basic Concepts, Conditions and Requirements 5 3.1.1 Calibrating the Instrument 6

3.2 Preparing Samples, Reference Materials and Standards 9 3.2.1 Analyses at trace level 10 3.2.2 Diluting samples - the working range of the ELEMENT 10 3.2.3 Preparing standard solutions 11

3.3 Carrying out Analyses with the ELEMENT 12 3.4 Preliminary Examinations and Semi-quantitative General Analyses 14

3.4.1 Semi-quantitative analysis 14 3.5 Matrix-Induced Interference of the Analysis Function 16

3.5.1 Element equations / high resolution 17 3.5.1.1 Background: element equations 18

3.6 Quantitative Analysis 18 3.6.1 Selecting the standardization procedure 19

3.7 Blank Correction 22 3.8 Using Internal Standards 23 3.9 Isotope Ratio Analysis 24 3.10 Flow Diagrams for Designing an Analysis 25

Table of Figures Figure 3.1 Diagram illustrating the concept of the accuracy of an analysis. 6 Figure 3.2 Graph of the calibration of a selected working range 7 Figure 3.3 Flow diagram showing how a selected working range is calibrated 8 Figure 3.4 Detection Limits 9 Figure 3.5 The ELEMENT response curve 15 Figure 3.6 Creating a new response curve 15 Figure 3.7 Systematic errors of the calibration curve. 16 Figure 3.8 Continuous spiking at constant volume 20 Figure 3.9 Standard addition calibration 20 Figure 3.10 Internal standardization of the response curve 23 Figure 3.11 Flow diagram for analysis planning: 25 Figure 3.12 Flow diagram for analysis planning 26



3 Designing an Analysis This section provides an introduction to using and operating the ELEMENT2. Details of how to operate the different programs, and their contents and functions, are described in the corresponding sections.

This part of the manual will discuss the essential steps in the planning of an analysis. There are three main areas:

General information on designing an analysis Specific problems of trace analysis with ICP-MS Carrying out analyses with the ELEMENT2

The description of analysis planning in this manual is mainly restricted to

demonstrating the correct application of the implemented functions of the ELEMENT software. The complete process for analyzing unknown sam-ples will be rather briefly described. The main emphasis is on demon-strating the development and implementation of quantitative analytical procedures. Paragraph 3.9 discusses the special characteristics of correct isotope ratio analyses.

The manual does not provide details of the statistical checking and

evaluation of calibration functions or analysis data in terms of quality as-surance in analytical chemistry (e.g. Good Laboratory Practice [GLP], ISO Guide 25, EN 45000 series). For additional information on those de-tails please refer to the relevant publications.

3.1 Basic Concepts, Conditions and Requirements Concept The objective of analysis planning is to develop a suitable concept for

the examination of samples in order to answer particular questions. For ICP mass spectrometry, this means the quantitative determination of element concentrations, and the determination of isotope ratios in vari-ous sample matrices.

Conditions The prevailing laboratory conditions, and the analytical requirements of

the user determine the required quality of the analysis:

Specificity: This describes the ability of an analytical procedure to detect only the desired analyte (the isotope) without other constituents of the sample (the matrix) affecting the analysis result.

Sensitivity: This provides a measure of the ability of an investigative procedure to

differentiate between adjacent values (e.g. concentrations). It is quanti-fied by the slope of the calibration curve.

Accuracy: The accuracy of an analytical procedure describes how well the average

of a number of determinations represents the real value.



Figure 3.1 Diagram illustrating the concept of the accuracy of an analysis. ANALYS.BMP

The qualitative limit of detection and the quantitative limit of determina-

tion are used to assess the effectiveness of an analytical procedure at extremely low concentrations.

The cost involved in analytical quality assurance depends initially on whether a new analytical procedure has to be developed, or whether a standardized analytical procedure can be applied.

Developing an For the purposes of this manual, developing a new analytical procedure Analytical Procedure means calibrating the ELEMENT2 for various types of sample. Although

the same ICP-MS principle is always applied, the use of different sample matrices makes it necessary to check the quality characteristics of the analytical procedure (see paragraph 3.3).

Applying Existing Applying existing analytical procedures in routine analysis means that

the Analytical Procedures quality assurance steps are restricted to the recalibration of the equip-

ment using a limited number of standards. The characteristics of the existing basic calibration are used to assess the accuracy of the analysis data.

3.1.1 Calibrating the Instrument Calibrating When calibrating the Instrument, a calibration function is obtained which

describes the measured value as a function of the concentration. Linear regression analysis is used as a simple mathematical model to deter-mine the calibration function. It assumes that the numerical values of the independent variable (the concentration) are already known before the analysis begins, and that these are correct (see also paragraph 3.2.3). The numerical values of the independent variable y (the measured val-ues) may contain random errors and will be determined in the calibration experiment.

The calibration function is the linear regression between the concentra-tions and the measured values. It is used to determine the concentration of elements in unknown samples. The determination of the statistical characteristics of the calibration allows the user to make objective state-ments concerning the accuracy of the analysis results.



The reason for restricting the description of the calibration function to a

simple linear regression is that a linear function adequately represents the data.

Carrying out Each calibration starts with the selection of a preliminary working range Standardization within which a linear calibration function may be expected, in line with

the given operational and measuring limits. This means that error-free determination is possible. The selection of the working range is based on the following criteria:

The working range should cover the expected concentration range of

the samples. The center of the working range should roughly corre-spond to the sample concentrations expected to be most prevalent.

The working range must correspond to the technical feasibility of the

system (see paragraph 3.2.2). The lower limit of the working range must not be below the determination limit of the analytical procedure; the upper limit of the working range is determined by either the maxi-mum permissible concentration or count rate.

The next step is to check the homogeneity of the variances of the work-

ing range selected. To do this, a variance F-test of the standard devia-tions of the measurement data which have been obtained from analyses carried out at the highest and lowest standard concentrations, should be performed. If there is no homogeneity of variances, then the working range has to be restricted, or the method of weighted regression has to be applied.

Checking the linearity of the selected working range requires the measur-

ing of several standard solutions of equidistant concentrations within the working range. A Mandel test for goodness of fit shows the linearity of the calibration function; if this is not linear, the working range needs to be restricted, or non-linear regression analysis applied.

Only after the working range has been checked the actual basic calibra-tion can be carried out. The number of different standard solutions used for the external calibration of analytical procedures should not be less than five (ten are recommended), in order to obtain statistical information of sufficient precision. Each standard concentration is determined sev-eral times in an irregular sequence.

Figure 3.2 and Figure 3.3 summarize this section.

Figure 3.2 Graph of the calibration of a selected working range 01REI.BMP



Figure 3.3 Flow diagram showing how a selected working range is calibrated

02AREI.bmp

Basic Calibration Basic calibration of the analytical procedure creates the conditions for

carrying out analyses with a precision which can be objectively characterized within a defined concentration range.

However, the user still has no information about the accuracy of the cali-

bration function for determining the concentration of the analyte in the particular sample matrix. Further preliminary examinations are required to discover any systematic analytical errors. Once the matrix interference effects have been determined, they form the basis for selecting a suit-able standardization procedure (paragraph 3.6).

The large working range of the ELEMENT makes it theoretically possible

to calibrate and analyze many elements, even those in complicated ma-trices, over large concentration ranges. The user should take into ac-count the fact that the linearity of the calibration function depends not only on the analyzer (the mass spectrometer), but is also determined by the properties of the ion source (the ICP). However, particular care is al-ways needed when checking the working ranges near determination lim-its, and at very high concentrations.

Inputs and Results

Operations

Branches

Calibration procedure working range x1....x2 step interval Dx number of analyses

Calibration data

TEST: variances homo-

geneous?

Alter working range

Weighted linear regres-sion

No No

Non-linear regression No TEST: linear?

Yes

No

Yes

Simple linear regression

Calibration function y= a0 + bx



In routine analysis, the extent of calibration in the various standardization

procedures is usually restricted to the use of only a few standard solu-tions. In order that acceptable levels of analytical precision can still be attained in spite of this, it is essential that the user is familiar with the working ranges of the ELEMENT for the particular applications intended.

3.2 Preparing Samples, Reference Materials and Standards The ELEMENT2's extremely high sensitivity enables it to carry out quanti-

tative analyses for virtually all elements in the ng/l range; for a number of elements, analyses in the pg/l range and beyond are also possible.

Figure 3.4 Detection Limits Periodic_1.tif

Although ultra-trace analysis is certainly the major use of ICP-MS, real samples generally contain a matrix of major and minor constituents which may be present in concentrations which are more than ten orders of magnitude higher than the ultra-trace levels.

This has consequences for the selection of suitable measuring programs,

for the prevention of damage to the detector (see Paragraph 3.3.1. and Paragraph 3.4.1.), and for the selection of suitable standardization pro-cedures to correct matrix interference effects (see Paragraph 3.5 and Paragraph 3.6.1.).

The basis of any chemical analytical method is, first of all, the prepara-

tion of the samples whose chemical constituents are to be determined, and the necessary standard or reference samples.



3.2.1 Analyses at trace level Analysis at the trace or ultra-trace level places extremely high demands

on the cleanliness of the laboratory and sample containers, and on re-agents and solvents. The high detection power of ICP-MS means that it is the blank levels of many frequently encountered elements such as Na, B, Ca, Fe, S, Cl, which impose the real boundaries on detection limits. When preparing samples and standards, if there is a risk of contamina-tion from the laboratory air (e.g. Zn, Cu, Fe etc.), then every step in the procedure which involves open sample containers should be carried out in special clean rooms or on clean benches. Only those containers whose constituent materials are sufficiently resistant and low in contami-nation should be used for the preparation and storage of samples. Tem-perature-resistant containers made of fluorinated polymers (PTFE, PFA, FEP, etc.) have proved suitable for sample preparation (e.g. digestion and extraction). Sample solutions are generally stored in clean plastic containers made of PE (polyethylene), PP (polypropylene) or PS (poly-styrene).

The purity of the reagents, reference materials, standard substances and

solvents used is of particular importance. To ensure low blank values, the reagents used - digestion acids, standard substances or solvents - must be of the highest levels of purity (quality levels: "suprapur", "ul-trapur", bi-/tridistilled), or may perhaps even have to be treated again (distillation, sub-boiling, crystallization, ion exchange).

A common problem of multi-element analyses is the contamination of

individual standard reagents by accompanying elements. For example, in cases where matrix-matched standard solutions with large excesses of major constituents need to be prepared, the standard reagents of the ex-cess constituents are often not commercially available at sufficient purity (see also Paragraph 3.5. and Paragraph 3.6.1., addition calibration).

1-3% nitric acid added to aqueous solutions has proved to be a good

solvent additive. The addition of the acid stabilizes solutions and mini-mizes wall effects in the sample containers. Other mineral acids should be avoided as far as possible, in order not to cause spectral interference by other elements (S, Cl, P, F, Br) (see Paragraph 3.5).

3.2.2 Diluting samples - the working range of the ELEMENT When preparing sample and standard solutions, attention should be paid

to proper dilution of the dissolved substances. As a rule, the salt content of relatively highly volatile materials such as Na, should not amount to more than 10 g/l, and the salt content of refractory elements such as alu-minum should not amount to more than 1 g/l, in order to prevent the nebulizer or the interface cones from clogging up.

Highly volatile matrix constituents such as acids and organic components can generally be tolerated, even in greater concentrations. However, at-tention should be paid to the fact that the dissolved constituents affect the viscosity and surface tension of the solutions, and thus the effective-ness of the nebulizer (see Paragraph 3.8., internal standardization). The measuring of concentrated salt solutions can result in considerable memory effects in the inlet system, so that correspondingly long rinse times need to be selected.



These concentration limits refer only to the maximum values acceptable

to the nebulizer and the interface, and not to the concentrations which are acceptable to the mass spectrometer or the detector. The highest concentration acceptable to the detector depends on the detection mode and the chosen resolution:

If the Both mode is chosen, the detector switches automatically be-

tween analog and counting mode.

For the digital counting mode, the concentrations should generally not be greater than 100mg/l at a resolution of R=300 for the upper mass range. The upper limit of the count rate for the digital counting mode is about 5*106 cps; at higher count rates, measurements must be made in the analog mode. The linearity of the calibration function, and the acceptable working ranges need to be checked for each par-ticular application (Paragraph 3.1.1.).

At a higher resolution, the upper limits increase in approximately di-

rect proportion to the ratio of the resolution.

In the analog mode, the concentration limits are in the mg/l range. To avoid damaging the detector, the mass ranges for skipping elements

which are too concentrated, may be reset. With frequently recurring ma-trices, this is ensured by making the appropriate entry in the Skip Masses dialog in the Executive program.

Therefore, for completely unknown samples, a general analysis of a di-

luted solution should be carried out in the both mode. After visually checking the intensities of the mass spectra in SHOW (see

Section 13), elements which are present in too high a concentration can be recognized, and the corresponding mass ranges avoided or higher di-lutions made.

The particular dilution of the samples should ensure that as many as possible of the elements for analysis are present in concentrations which correspond to the acceptable working range of the analytical procedure (see Paragraph 3.1.1). This may sometimes be impossible with multi-element analyses of real samples, and several dilutions may need to be prepared.

The determination of the dilution factor, and the accuracy of the dilution

of samples and standard solutions, decisively determine the quality of the analysis; for this reason, the user should aim for a relative error of 1% or less. It is therefore necessary to use calibrated scales, volumetric flasks and pipettes, as well as certified standards.

3.2.3 Preparing standard solutions Standard solutions must be of the highest quality in order to avoid gen-

erating additional errors when calibrating the method. The assumed free-dom from error, or the negligible error of standard concentrations (the "x values" of the calibration function), is a basic condition of normal calibra-tion procedures (Paragraph 3.1.).



The general requirements stated in Paragraph 3.2.1. and Paragraph

3.2.2. for the handling, storage and dilution of samples should be ad-hered to.

In the production of standard solutions for external standardization, the

preliminary working range of the analysis is covered in 5 to 10 equidis-tant concentration steps. The preparation of one dilution from another should be avoided if possible, so that the perpetuation of errors is avoided. Each standard solution should be made individually from a cer-tified solution.

When preparing spiked solutions for the addition calibration or standard

addition method, it should be ensured that the volume of the added spikes is as small as possible in relation to the sample volume. The con-centrations in the added spikes are therefore considerably higher than in the samples themselves (factor 10 -100). The standard additions are car-ried out in accordance with the procedure of continual spiking at constant total volume, as is described in Paragraph 3.6.1.

3.3 Carrying out Analyses with the ELEMENT The essential applications of ICP mass spectrometry can be character-ized as follows:

Application Use Characteristics Semi Quantitative analysis Fast general analyses of

unknown samples to as-sess the element composi-tion

Calibrates a general response curve using only standards and selected elements, undefined accuracy

Quantitative analysis Correctly determines the element content

Calibrates using sev-eral standards and all analyte elements, de-fined accuracy

Isotope ratio analysis Determines the relative abundance ratios of two isotopes

Corrects mass dis-crimination using the external or internal standards of known isotope ratios

Isotope dilution analysis Determines the contents of polyisotopic elements with high accuracy. Allows the correction of recoveries of sample preparation steps (extractions etc.)

Calibrates using stan-dards with enriched isotopes of known con-centrations. Adds spikes before sample preparation

Table 1 Types of Analyses



In addition, there is the option of displaying each mass spectrum graphi-

cally with the aid of the SHOW program, and performing manual evalua-tions (e.g. peak integration).

Analyses carried out using the ELEMENT2 follow the same pattern for the

various applications. The analysis sequence can be summarized for all applications by the following steps (essential contents):

1.) Starting operation

(Ignition of the plasma, tuning the instrument, checking mass cali-bration)

2.) Preparing sample, standard and blank solution (dilutions / concentrations)

3.) Creating a measuring program (mass ranges, measuring time, measurement modes)

4.) Creating standard and internal standard files (stating the elements to be evaluated, their concentrations in the standard solutions, as well as the internal standard elements and their concentrations)

5.) Creating a sample sequence

(blanks, samples, standards)

6.) Starting measurements

7.) Evaluating and displaying measurement data

7 a.) Evaluating measurement data ((semi-) quantitative and iso-tope ratio analysis, displaying transient signals and raw data)

7 b.) Graphically displaying and evaluating the spectra ((visual assessment of spectra (including online), manual evaluation of signals)

The effort required to examine real samples depends on the question

posed, and on the laboratory conditions. Two cases need to be distin-guished:

where existing analytical procedures are applied to known or compa-

rable types of samples; where new analytical procedures are developed for more or less un-

known samples.

The development of a new analytical procedures is more time-consuming, and it is generally necessary to determine the properties of at least the partly unknown samples by preliminary examinations.



3.4 Preliminary Examinations and Semi-quantitative General Analyses Preliminary examinations of new samples are not restricted to the cases

which involve completely unknown samples. Simple preliminary exami-nations of the types of samples whose origins enable the user to draw conclusions about the matrix constituents and analyte concentrations which may be expected, can save considerable analysis time.

The goals of preliminary examinations can be summarized as follows:

to determine the major and minor constituents:

- choose the appropriate dilution - obtain information about the matrix or check for matrix interference effects (see Paragraph 3.5)

to determine the analytes semi-quantitatively

to determine the homogeneity of the collection of samples.

The investigation of an unknown sample starts with a general analysis.

The sample is sufficiently diluted (see Paragraph 3.2.2.) and then meas-ured. The analysis data are presented using the graphical display of the mass spectra in SHOW (see Section 13).

The evaluation of the mass spectra in SHOW provides an indication of

the concentration ratios of the trace constituents. Simple and rapid evaluation of the mass spectra in SHOW reduces the time needed for the preliminary examination of a sample to a few minutes.

The preliminary examinations provide the user with the essential infor-

mation needed to carry out the actual (semi)quantitative analyses:

information on the major, minor and trace constituents information on suitable sample dilutions.

3.4.1 Semi-quantitative analysis In semi-quantitative analysis, the assumption is made that each isotope

has a defined, instrument-specific response [cps/concentration]. In con-trast to the response curve of a Quadrupole ICP-MS device, the re-sponse curve of the ELEMENT is practically a linear function of the mass-to-charge ratio. The response curve is calculated with the aid of linear regression, using the measured intensities of the elements of the standard solution (single-point calibration). The measured intensities of these isotopes are normalized to an abundance of 100% using the known isotope ratios, so that a linear response curve of mass-to-charge ratio vs. response results. This is shown in Figure 3.5 below. Using the simple rule of three yields the content of an unknown sample as the ratio of the measured counts and the normalized counts of the re-sponse curve.



Figure 3.5 The ELEMENT response curve 03REI.BMP

However, the absolute value of the measured count (rate) depends on

many parameters:

the particular "state" of the instrument on a particular day; the par-ticular optimization, condition of the cones, torch etc.

the type of solution and the effectiveness of the nebulizer; the vis-cosity, density, vapor pressure, salt content etc. of the solutions; the condition of the nebulizer etc.

spectral and non-spectral matrix interference effects (Paragraph 3.5.).

It is thus necessary to adjust the absolute count rate of the response

curve to the prevailing conditions. When carrying out external calibration or adjustment of the response curve, a standard solution with a limited selection of elements from various mass ranges is measured. The selec-tion and number of the standard elements is based on the mass range which is to be analyzed, and the required certainty of the response curve adjustment. To evaluate the external calibration, the existing basic calibration is adjusted using the current counts of the standard elements AX, BX and CX (Figure 3.6):

Figure 3.6 Creating a new response curve 05REI.BMP

response



This procedure allows direct measuring of unknown samples without any further pretreatment (note the dilutions which are necessary, see Para-graph 3.2.2.) and is thus suitable for a very quick, general analysis. This procedure is, however, susceptible to drift effects or changes in instru-ment response and it provides few indications by which non-spectral ma-trix interference effects can be recognized (see Paragraph 3.5). This pro-cedure should therefore only be used with simple sample matrices which show little variation. The use of internal standard elements is highly rec-ommended in order to correct drift effects (Paragraph 3.8); this also ap-plies to quantitative analyses (Paragraph 3.6.). Semi-quantitative analysis is distinguished from quantitative analysis in two ways: the Semiquantitative calibration can be restricted to only a few standard samples of elements in the mass range to be analyzed, and also, only one concentration of standard solutions is used (see Paragraph 3.6.). The problem of blank-value correction is dealt with in Paragraph 3.7.

3.5 Matrix-Induced Interference of the Analysis Function Matrix-induced interference of the analysis function must be taken into

account even with high-resolution ICP-MS. In addition to the spectral in-terference caused by molecular ions or isobars, non-spectral signal inter-ference is also of importance.

It can be seen, for example, that high concentrations of alkaline or alkali earth elements result in signal reductions across the entire signal range. However, matrix-induced enhancement of signal peaks have also been observed. Here, it is found that the extent of the interference may be de-pendent on the mass-to-charge ratio. Neighboring isotopes of an element may suffer varying degrees of inter-ference as a result of the so-called mass discrimination effect (e.g. 206Pb,207Pb, 208Pb). It is therefore necessary for isotope ratio analyses to correct this effect using standards of known isotope ratios (Paragraph 3.9.). The cause of non-spectral interference by matrix components is re-lated to the ion optics of the mass spectrometer and/or effects in the ion source or interface region.

Experience in using the ELEMENT has shown that, besides reducing spectral interference, it also produces smaller non-spectral matrix inter-ference effects. Nevertheless, each individual case should be examined to see whether matrix interference effects may be involved.

The influence of matrix interference effects on the analysis function is shown in Figure 3.. The dotted lines show the measured count of an ele-ment in a solution containing a matrix, while the unbroken lines show the

calibration lines for a matrix-free standard.

Figure 3.7 Systematic errors of the calibration curve. 06REI.BMP



The calibration of an analytical procedure with the ICP-MS must always take into account the matrix and its variance when considering which samples to use. However, such effects are not only observed in obvious excess conditions, but may also appear in relatively diluted solutions with unfavorable compositions.

The development of an analytical procedure therefore requires that the

presence of systematic errors be checked, and that they be corrected us-ing appropriate standardization procedures. The determination of the precision of an analytical procedure was discussed in paragraph 3.1.1; the examination of matrix interference effects involves checking the accuracy of the procedure.

The following phenomena indicate signal interference effects due to the

sample matrix:

Clearly differing signals of plasma-induced molecule ions such as ArC+ or ArH+ between matrix-free standard solutions and samples.

The selected internal standards (Paragraph 3.8) behave differently in external standards than in real samples (different intensities or in-tensity ratios, different behavior in response to the variation of in-strumental parameters such as the nebulizer gas flow).

Non-proportional signal reductions with sample dilutions within the normal linear working range (signal interference dependent on the matrix concentration).

The slopes of the calibration functions of external calibration and standard addition mode differ (see Paragraph 3.6.1, proof of multi-plicative matrix influence).

The y-intercept of the straight calibration lines is not equal to zero in spite of simple blank-value correction, and increased blank values are detected when using matrix-adapted external standards; The user needs to ensure that these have not been introduced by impuri-ties (see Paragraph 3.6.1, proof of constant systematic matrix influ-ence due to insufficient analysis selectivity).

It is therefore necessary to use calibration procedures which make it

possible to recognize and compensate for matrix interference effects - this explains why the standard addition method or the addition calibration need to be applied (Paragraph 3.6.1.) in order to detect and correct sys-tematic multiplicative deviations. Constant systematic effects, on the other hand, are much more difficult to detect. They generally require ref-erence analysis with an independent method or the analysis of standard reference materials, if matrix-adapted blank solutions are not available.

3.5.1 Element equations / high resolution In order to reach acceptable detection limits for a number of elements

which are subject to severe interference in Quadrupole ICP-MS, the use of element equations to correct spectral interference is an essential tool.

In high-resolution element mass spectrometry, it is usually possible to manage without element equations by selecting the appropriate resolu-tion. This is not possible with isobaric interferences, however, and the in-tensity of the interfering isotope is simply corrected using the known natural isotope ratio.



3.5.1.1 Background: element equations For the element equations, the formation rate of the interfering molecule

ion relative to an undisturbed isotope is determined by preliminary ex-aminations. Using the known natural isotope ratios of the elements, a correction equation for the computation of the intensity component of the interfering ion in a signal is thus obtained. The basic disadvantage of us-ing these correction equations, however, is the reduced accuracy due to error propagation in the calculation of the analysis results from the vari-ous signal intensities.

The following examples are intended to show the computation of ele-ment equations:

1. 40Ar35Cl interferes with the mass of mono-isotopic 75As. The intensity

of 40Ar35Cl can be calculated using the isotope ratio of 35Cl to 37Cl via the measurement of 40Ar37Cl:

I(75As) = I(75[m/z] - I (40Ar35Cl) I = intensity I(40Ar35Cl) = I(77[m/z] -x (a35Cl/a37Cl) a = abundance

2. The isobar overlap of 94Mo interferes with the measurement of 94Zr. The intensity of 94Mo can be computed using the measurement of 95Mo on the basis of the known isotope ratio:

I(94Zr) = I(94[m/z] - I (94Mo) I(94Mo) = I(95[m/z] -x (a94Mo/a95Mo)

3.6 Quantitative Analysis To develop a quantitative analysis method, a calibration of all the ele-

ments to be determined should be carried out using appropriate standard solutions. The concentration range of the samples should be covered by the appropriate selection of various concentrated standard solutions. Multi-element procedures may result in the measuring of elements ac-cording to the concentration range and ratios in various dilutions. This is why the information gained from Semiquantitative analysis is very impor-tant (Paragraph 3.5.) in cases of unknown samples and in the develop-ment of new analytical procedures. It determines how one proceeds, and which calibration method should be selected (Paragraph 3.6.1.).

When calibrating an analytical procedure, it is important to first of all

select a preliminary concentration range which corresponds to the practi-cal requirements and the technical possibilities. A linear calibration func-tion, which allows considerably simpler statistical evaluation of the analysis data, is desirable (Paragraph 3.1.1.). The calibration provides the necessary characteristics of the method for a tested working range: coefficients of the analysis function, standard deviation of the method, confidence interval, limits of detection and determination.

The analysis function (concentration = function [measured value]) is

given by the inverse of the calibration function (measured value = func-tion [concentration]), thus converting the measured value into the analy-sis result.



Even the use of several internal standards (Paragraph 3.8) does not

dispense with the need to carry out a complete basic calibration of each element to be analyzed, nor for the appropriate examinations of the ma-trix interference effects. Internal standards are no substitute for calibra-tion functions. It is again emphasized that there is an essential difference between the development of an analytical method for the determination of procedure characteristics, and the routine recalibration of existing methods. The extent of the calibration depends on the requirements made of the analysis result, as stated in Section 2. For a quantitative analysis, however, there are certain minimum requirements concerning precision (RSD < 20%) which must be met. This manual can only give instructions to the extent that they are necessary to obtain quantitative data. Details of standard calibration techniques and evaluation methods must therefore be taken from the specialist literature.

3.6.1 Selecting the standardization procedure The following standardization procedures are available for the quantita-

tive determination of element concentrations. The use of internal stan-dardization is recommended for all procedures (Paragraph 3.8.); it is automatically included in the isotope dilution analysis. The problem of blank-value correction is dealt with in Paragraph 3.9.

External calibration External calibration uses standard solutions of the elements to be ana (with internal standards) lyzed, and blank values of the reagents and solvents used. In order to

control equipment-induced drift effects, suitable internal standards should be used. The concentration range of the standards must cover the desired working range; at least three different standards (one degree of freedom) are necessary per analysis. If the elements are present in vastly differing concentrations, or if there are solubility problems with some multi-element standard solutions, the calibration can be carried out in different element groups (multi-bottle procedure). However, external calibration is only to be recommended when no matrix interference ef-fects appear. Correction of matrix interference effects where the sample matrices do not vary excessively, is possible using matrix adjustment of the external standards (see addition calibration).

Standard addition In this method, the concentration of the element to be analyzed is spiked

in every sample in at least three individual steps. The total quantity of each element added in the individual steps should correspond to the con-tent of the original sample (csample); it should be ensured that the total content of the spiked samples is within the linear working range. To avoid dilution effects caused by the added spikes, the addition solution should be considerably more concentrated than the measuring samples, so that the ratio of spiked solution to sample volume is as low as possi-ble (Paragraph 3.2.3.). It is nevertheless recommended that this ratio is made up to a constant sample volume (original sample + spikes + sol-vent = constant) with appropriate additions of the pure solvent. This pro-cedure is shown in Figure 3..



Blank values of the method have to be corrected by measuring the ap-

propriate "blanks" (Paragraph 3.8.). The use of internal standards serves to correct equipment-induced drift effects (Paragraph 3.8.). Since, in this procedure, calibration takes place in the real matrix of each individual sample, multiplicative systematic deviations of the calibration curve are corrected. One disadvantage is the considerably longer measuring time needed (each sample must be measured four times) and the more time-consuming sample preparation method.

Figure 3.8 Continuous spiking at constant volume 07rei_x02.jpg

The following figure shows the evaluation of the standard addition method:

Figure 3.9 Standard addition calibration 08REI_xb.jpg



Addition calibration or This method is a compromise between external calibration and the stan matrix-adjusted dard addition calibration method. Where samples show matrix interfe external calibration rence effects but their composition is relatively uniform, (e.g. seawater or

processed water samples), external calibration can be carried out by ap-plying the standard addition method to one real sample. In cases where there are slight variations in the matrix composition, the addition calibra-tion method should be checked by additionally measuring samples at certain intervals with a single standard addition, in order to check the slope of the straight calibration lines.

Where possible, a matrix which is not too complicated can also be simu-

lated using appropriately prepared standards. This makes it possible to generate the sample matrix without the element you wish to analyze, and to thus obtain indications of constant systematic deviations.

The problem is, however, that not enough pure standard substances which do not already contain the trace constituents to be analyzed, are available for the manufacture of matrix-adjusted standards. To correct constant systematic deviations, an analysis of certified standard refer-ence materials must be made, or an independent reference method ap-plied.

Isotope dilution Isotope dilution analysis using stable isotopes and an ICP-MS is a stan-

dardization procedure providing inherently highly accurate quantitative analysis.

With isotope dilution analysis, the natural isotope ratio of an element in

the sample is compared with the isotope ratio after the addition of a known quantity of the element with an enriched isotope.

This has the considerable advantage that only the intensity ratio of two

isotopes is determined simultaneously and in the same matrix. This com-pensates for the fluctuations in instrumental parameters which occur during internal standardization (Paragraph 3.8.). In contrast to conven-tional internal standardization, however, the same element is added, so that multiplicative systematic matrix interference effects are corrected. For this same reason, it is also possible to add the spike solution before sample treatment, thus avoiding the problems with the percentage re-coveries which arise in sample preparation techniques.

The basic limitations of the method can be summarized in the following

points:

Spectral interference effects are not automatically compensated for, and must therefore be corrected using element equations (Paragraph 3.5.1.) or blank-value subtraction (Paragraph 3.7.).

The precision of isotope dilution analysis with ICP-MS is limited by

the standard deviation of the measured signal intensities which de-termine the error of the computed isotope ratios according to the law of error perpetuation.



Summary In order to be able to make the decision as to which calibration method

should be applied, and how, it is always necessary to have preliminary information on the samples to be examined (Paragraph 3.4.). Although cases in which the constituent elements of the samples are completely unknown, are rare, it is generally difficult to predict the behavior of ana-lytes in a variable matrix. In addition, it is necessary to have some knowledge of the working range of the ICP-MS multi-element analysis for the elements to be investigated, in order, for example, to maintain the linear working range for element groups as large as possible by means of appropriate dilutions.

The criteria for the selection of a suitable standardization procedure are summarized in the flow diagrams in Paragraph 3.10.

3.7 Blank Correction The observation of blanks of the method plays a special part in trace

analysis. All frequently occurring elements (e.g. Na, Ca, Zn, Cu and many others) can only be analyzed at the trace or ultratrace level if spe-cial precautionary measures have been taken, because the blanks of these elements are often so high that they severely affect the limits of detection.

The element concentrations measured in the analysis must therefore be

corrected by the existing blank values of the method. For this purpose, the blank samples used should be subjected to the same procedural steps as the actual original samples (e.g. digestion, extraction, etc.). The blank value may be caused by impurities in the samples (reagents, con-tainers, solvents, etc.) or by spectral interference, for example. On ac-count of the high degree of selectivity of high-resolution mass spec-trometry, the problem of constant systematic deviations is reduced to a few special examples. The most important interferences, and the re-quired resolutions, are presented in the tables provided. Isobaric interfer-ences, which cannot be removed even at a resolution of R = 10,000, are compensated for by appropriate corrections (Paragraph 3.5.1).

Measured sample concentrations should not be corrected by directly

subtracting the blank values of the method, however. It is usual to treat blank samples of the method like normal samples, and to only directly subtract the blank values of the measurement of the pure solvent used (e.g. doubly distilled water, possibly with acid additives, see Paragraph 3.2.1.). This allows direct control of the blank value concentrations. The measured blank values are only subtracted after the sample concentra-tion has been evaluated.

In order to discover memory effects during the analysis of a sample se-

quence, blank samples are analyzed regularly within a sequence.



3.8 Using Internal Standards For internal standardization, elements are selected which are not present

in the sample at all, or only in negligible concentrations. The internal standard elements are always added to the sample aliquots to be ana-lyzed in the same concentration. The measured intensities of the internal standard elements would therefore remain constant in samples and standard solutions, were they not exposed to the influences described in Paragraph 3.4.1. and Paragraph 3.5.

The change in the signal intensities of internal standard elements thus serves to check and mathematically correct variable instrumental parameters and other influences on the raw data obtained. For this purpose, the meas-ured intensities of the measurements are di-vided by the intensity and concentration of the internal standard elements, and thus stan-dardized. Figure 3. shows the effect of inter-nal standardization using the response curve of Semiquantitative analysis.

Figure 3.10 Internal standardization of the response curve 09REI.BMP

However, this assumes that the internal standard elements behave suffi-ciently like the isotopes to be analyzed, and that they themselves do not generate a matrix effect (see Paragraph 3.5.). This results in the re-quirement that the concentrations of the internal standards must ap-proximately correspond to those of the elements to be analyzed.

Internal standard elements are used in the ICP-MS analysis to compen-

sate for drift effects of response or measured intensities. The variety of parameters which affect the absolute sensitivity of the method (Para-graph 3.4.1.) make it virtually imperative to apply internal standardization to the analysis of real samples.

In addition, the use of several standards makes it necessary to carry out

a complete basic calibration, as well as the appropriate examinations of the matrix interference effects, for each element to be analyzed. In par-ticular, internal standards are no substitute for calibration functions.

Since the internal standard elements are exposed to the same non-spectral matrix interference effects or mass discriminations as the ana-lytes themselves, the latter can be corrected by internal standard ele-ments only over a very restricted mass range of a few Dalton, if indeed at all. The use of an internal standard can, however, provide initial indi-cations of possible matrix interference effects (see Paragraph 3.5.).

Hence, internal standardization serves primarily to check fluctuating

instrumental parameters. The addition of internal standards before samples are prepared is used to check the procedural steps of an analysis, e.g. with regard to the re-covery (see also Paragraph 3.6.1, isotope dilution analysis), but this is not the subject of this manual.



3.9 Isotope Ratio Analysis ICP-MS provides the option of fast isotope ratio analysis. Applications to

determine isotope ratios can be found primarily in geochemistry, nuclear technology, medicine and environmental analysis.

To determine isotope ratios, high precision and accuracy are necessary,

since the difference in the isotope ratios is usually very small. The precision of intensity determination is, as is the case with quantita-

tive analysis, essentially determined by the total number of counts ob-tained, and also the instrument-specific fluctuations. For this reason it is important to ensure appropriate adjustment of measurement times when measuring isotopes with very different abundancies.

Isotope ratio standards are measured in order to ensure that the meas-

ured intensity ratio corresponds to the true isotope ratio. With mass spectrometric determinations of isotope ratios, the measured

intensity ratio must generally be calibrated using internal or external standards of known isotope ratios. The reason for this is linked to the mass-dependent sensitivity of the mass spectrometer, which results in systematic errors even where there are slight mass differences in the iso-tope of an element. This effect is referred to as mass discrimination. In addition, matrix-induced interference (Paragraph 3.5.) and blank values (Paragraph 3.7.) must be taken into account.

To correct systematic deviations, factors are determined using external

or internal standards which allow the conversion of intensity ratios into isotope ratios.

External calibration uses certified standards with known isotope ratios.

The measured intensity ratios of the samples to be examined are cor-rected according to the following formula:

isotope ratio of element

X measured intensity ratios Z= certified isotope ratio

Elements with known isotope ratios, whose mass is a neighboring mass

of the element to be determined, can be used for internal standardization (e.g. 203/205Tl can be used to determine the isotope ratio 206/207Pb. The known isotope ratio is then used to correct for mass bias in the ratio to be determined.

The basic disadvantage of internal standardization is linked to the condi-

tion that the mass discrimination effect for the internal standard has to correspond to the mass discrimination effect of the isotope to be deter-mined. This has to be checked in each individual case. External calibra-tion is therefore normally used in preference to internal standardization.

Standard

Standard

Sample

Sample

X

X

X

X

X

X

IaIb

*Z*IbIa

ba

=



Measurement ofSamples

BlankSamples

Thermo Finnigan ELEMENT2 Operating Manual

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