Inorganic Trace Analysis
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Transcript of Inorganic Trace Analysis
TraceSELECT®– High Purity Reagents for...
■ Sample Preparation
■ Analysis
■ Calibration
Inorganic Trace Analysis
2 sigma-aldrich.com/traceselect sigma-aldrich.com/techservice
• Produced and certified in double accredited laboratory according to ISO/IEC 17025 and ISO Guide 34
• Unique level of accuracy & lot specific certified values incl. uncertainty
• Traceable to at least two independent references (i.e. NIST, BAM or SI unit kg)
• Highly sophisticated packaging & documentation with expiry date
• ICP standards list up to 70 trace impurities
TraceCERT®
Swiss Precision Meets Analytical Competence
Ordering InformationFind our actual list of TraceCERT reference materials for calibration and method validation at http://www.sigma-aldrich.com/tracecertFor custom standards please contact us at: [email protected]
Traceable Certified Reference Materials for ICP, AAS and IC
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Inorganic Trace AnalysisTable of Contents
Introduction ................................................................................................................................................................. 4
Sample Preparation for Trace Analysis: TraceSELECTUltra and TraceSELECT ........................................................ 6
Trace Analysis: High Purity Reagents ........................................................................................................................ 8
Matrix Modifiers .................................................................................................................................................... 8
Spectroscopic Buffers for Flame AAS ..................................................................................................................... 8
Reducing Agents for Hydride AAS ......................................................................................................................... 8
Solvents for Trace Metal Speciation Analysis .......................................................................................................... 9
Certified Eluent Concentrates and High Purity Water for Ion Chromatography ..................................................... 10
Ultra Pure Reagents for Voltammetry ................................................................................................................... 10
Calibration for Trace Analysis: TraceCERT - Certified Reference Materials ..........................................................11
Fluka-brand TraceSELECT and TraceSELECTUltra reagents from Sigma-Aldrich include high purity acids, bases and salts designed for trace and ultra-trace analysis.
For a complete list of products, visit our website:
sigma-aldrich.com/traceselect
• Produced and certified in double accredited laboratory according to ISO/IEC 17025 and ISO Guide 34
• Unique level of accuracy & lot specific certified values incl. uncertainty
• Traceable to at least two independent references (i.e. NIST, BAM or SI unit kg)
• Highly sophisticated packaging & documentation with expiry date
• ICP standards list up to 70 trace impurities
TraceCERT®
Swiss Precision Meets Analytical Competence
Ordering InformationFind our actual list of TraceCERT reference materials for calibration and method validation at http://www.sigma-aldrich.com/tracecertFor custom standards please contact us at: [email protected]
Traceable Certified Reference Materials for ICP, AAS and IC
4 sigma-aldrich.com/traceselect sigma-aldrich.com/techservice
IntroductionAs a supplier of analytical reagents
and standards, quality assurance is of
prime importance to Fluka. We
employ a comprehensive Quality
Assurance System according to EN
29001 (ISO 9001). Each of our more
than 20,000 products is manufac-
tured to clear, guaranteed specifications. The large variety
of modern analytical methods (e.g., ICP-OES, ICP-MS,
flame AAS, graphite furnace AAS) allows for specifically
tailored control and analysis procedures for each product.
Reagents for Inorganic Trace Analysis
Sensitive trace analysis applications require extremely
pure sample preparation reagents. These digestive
reagents cannot contain metal ions or other impurities.
Further, complete decomposition of the sample is required
to achieve reproducible and accurate elemental results by
instrumental analytical methods.
Sample wet digestion/dissolution is a method that
breaks down the components of a matrix into simple
chemical forms. This digestion can occur with the
introduction of energy, such as heat; by using a chemical
reagent, such as an acid; or by a combination of the two
methods. Most analytical measurements using highly
sensitive methods (AAS, ICP-AES, stripping voltammetry,
ion chromatography, etc.) are performed on samples in
solution. One of the most effective and economical
sample preparation methods is microwave digestion. In
most cases, achieving homogeneity and mineralization of
the sample is sufficient.
UV photolysis using hydrogen peroxide and either
potassium persulfate or nitric acid is very often the
method of choice for the decomposition of organic
impurities in aqueous solutions.
The most commonly used reagents for wet decomposi-
tion are mineral and oxidizing acids. Wet decomposition
has the advantage of being effective on both inorganic
and organic materials. It often destroys or removes the
sample matrix, thus helping to reduce or eliminate some
types of interference. Table 1 provides an annotated
overview of the acids used for wet digestion.
Table 1. Digestion/Dissolution Acids and Bases
HNO3
Nitric acid is the most frequently utilized sample dissolu-
tion medium. It oxidizes metals not dissolved by HCl and
other non-oxidizing acids. Au, Pt metals (expect Pd), Nb,
Ta, and Zr are not dissolved. Al and Cr are passivated. Sn,
Sb, and W give insoluble hydrous oxides. Dissolves most
sulfides (except HgS). Unfortunately, the carbon con-
tained in organic materials is only partly converted to CO2
by HNO3 at temperatures up to 200 °C. Nitric acid should
never be used for the digestion of highly aromatic
compounds because of the potential for the formation of
highly explosive compounds. In the case of alcohols, the
samples should be pretreated with sulfuric acid.
HClHydrochloric acid is used for many salts of weak acids,
e.g., carbonates, phosphates, some oxides, and some
sulfides.
H2SO4 Sulfuric acid is used when its high boiling point (300 °C)
is an advantage, as in expelling a volatile product or
increasing the reaction rate. It provides dehydrating and
oxidizing properties at high temperatures.
HClO4 Perchloric acid is a very powerful oxidizing agent at
fuming temperatures (boiling point 203 °C). It is usually
mixed with HNO3 to oxidize easily attacked organic
matter that might otherwise react violently with HClO4.
H2SO4 (dehydrating agent) increases oxidizing power.
Good solvent for stainless steel and for sulfides.
HF Hydrofluoric acid is used for digestion of silacaceous
samples and as an auxiliary reagent to HNO3 or HClO4 to
eliminate fluoride. With HNO3, HF dissolves Ti, W, Nb,
and Zr (and their carbides, nitrides, and borides) as a
result of formation of complex fluorides. Certain refrac-
tory silicates and other minerals are not decomposed;
these must be dissolved by fusion.
5sigma-aldrich.com
H2O2 Hydrogen peroxide is a very popular oxidizing reagent
as it is converted to water and oxygen during the
oxidation of biological material. Additional advantages
are that there is no acid corrosion of the digestion
vessel PTFE walls, no formation of insoluble salts with
an acid anion, and no change of the sample matrix by
an acid. Because of its strong oxidation power, only
small amounts of H2O2 need be used so concentrated
sample solutions can be obtained.
AcOH Acetic acid is most often used for the extraction of
metallic impurities together with sodium acetate.
HBrHydrobromic acid is a non-oxidizing acid. It is used in
some special applications because it yields better
reductive selectivity in the determination of Se(VI) by
Hydride Generation-Laser Induced Fluorescence
(HG-LIF) than HCl.
H3PO4 Phosphoric acid is commonly used in the semiconductor
industry to both clean and etch metal surfaces. The
concentration of the phosphoric acid is critical to
optimizing these processes.
H2O Water ensures the highest accuracy in trace analysis of
ppt range by minimizing blank values.
TMAH Tetramethylammonium hydroxide [(CH3)4NOH] is an
efficient strong alkali used for solubilizing soft tissues
and food stuffs. Compared to conventional alkaline
sample digestion procedures using NaOH or KOH, using
TMAH enables more accurate analysis due to its lower
matrix effect. A diluted 0.3 M TMAH solution is also
used during the lithographic process in the semicon-
ductor industry.
NaOHSodium hydroxide is frequently used for melting
digestions at 500 °C. It attacks platinum and porcelain.
Residue is dissolved with 12 M hydrochloric acid.
Please see our entire selection of high purity digestion reagents at sigma-aldrich.com/traceselect
1. Feng, X.; Wu, S.; Wharmby, A.; Wittmeier, A. Microwave digestion of plant and grain standard reference materials in nitric and hydrofluoric acids for multi-elemental de-termination by inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom. 1999, 14, 939–946.
2. Golimowski J.; Golimowska, K. UV photooxidation as pretreatment step in inorganic analysis of environmental samples. Anal. Chim. Acta. 1996, 325, 111–133.
3. Vandecasteele, C.; Block, C. B. Modern Methods for Trace Element Determination; Wiley: Chichester, UK, 1997; pp 1–8.
4. Sampling and Sample Preparation; Stoeppler, M., Ed; Springer: Berlin, 1997.
5. Sah, R. N.; Miller, R. O. Spontaneous reaction for acid dissolution of biological tissues in closed vessels. Anal. Chem. 1992, 64, 230.
6. Inductively coupled plasmas in analytical atomic spectrometry; Montaser, A.; Go-lightly, D. W., Eds.; VCH: New York, 1992; pp 473–516.
7. Tracy, M. L.; Moeller, G. Continuous flow vapor generation for inductively coupled argon plasma spectrometric analysis; Part 1: Selenium. J. Assoc. Off. Anal. Chem. 1990, 73, 404–410.
8. Pacquette, H. L.; Elwood, S. A.; Ezer, M.; Simeonsson, J. B. A comparison of continu-ous flow hydride generation laser-induced fluorescence and laser-enhanced ioniza-tion spectrometry approaches for parts per trillion level measurements of arsenic, selenium and antimony. J. Anal. At. Spectrom. 2001, 16, 152–158.
9. Sun, Y. C.; et al. Combining electrothermal vaporization inductively coupled plasma mass spectrometry with in situ TMAH thermochemolysis for the direct determination of trace impurities in a polymer-based photoresist. J. Anal. At. Spectrom. 2006, 21, 311–316.
10. Jeitziner, M. High-purity TMAH for alkaline digestion of biological samples. Analytix 2008, 1, 17.
KOH Potassium hydroxide is frequently used for melting digestions
at 500 °C. It attacks platinum and porcelain. Residue is
dissolved with 12 M hydrochloric acid.
K2CO3 Potassium carbonate is the classic reagent for melting diges -
tions at 800 °C. Residue is dissolved with hydrochloric acid.
6 sigma-aldrich.com/traceselect sigma-aldrich.com/techservice
Sample Preparation for Trace Analysis: TraceSELECTUltra and TraceSELECTUltra-pure acids, bases, and salts for smelting and wet digestion in environmental, water, and food analysis
Sample preparation for trace
analysis requires reagents of the
highest purity. Our TraceSELECTUltra
products for ultra-trace analysis at ppb
and even ppt levels are produced by
sub-boiling distillation. Sub-boiling is
recognized as the best way to obtain
high purity acids with the lowest blank
values for ultra-trace analysis. The
technique is based on the evaporation
of liquid by infrared heating at the
surface. It avoids violent boiling and
the formation of liquid aerosols that
can be transported with the distillate.
To maintain their high purity,
TraceSELECTUltra products are
supplied in PTFE PFA (fluoropolymer)
bottles. Water and ortho-phosphoric
acid are supplied in specially pre-
leached HDPE bottles. Recent process
improvements have allowed us to
reduce our impurity specifications in
order to guarantee the lowest levels of
trace impurities in our TraceSELECTUl-
tra products.
For more information, see our Web
site: sigma-aldrich.com/traceselect
Table 2. TraceSELECTUltra reagents
Cat. No. Brand Product Name Specification Pack Sizes
07692 Fluka Acetic acid 99.0 % (T) 250 mL, 1 L
16748 Fluka Ammonium hydroxide solution 25 % (T) 250 mL, 1 L
23828 Fluka Hydrobromic acid 44 % (T) 250 mL, 1 L
96208 Fluka Hydrochloric acid 30 % (T) 250 mL, 1 L
02658 Fluka Hydrofluoric acid 49 % (acidimetric) 250 mL, 1 L
16911 Fluka Hydrogen peroxide solution 30 % (RT) 250 mL, 1 L, 5 L
02650 Fluka Nitric acid ~ 65 % (T) 250 mL, 1 L
12415 Fluka Perchloric acid 67-72 % (T) 250 mL, 1 L
64957 Fluka Phosphoric acid 85 % (T) 250 mL, 1 L
77239 Fluka Sulfuric acid 95 % (T) 250 mL, 1 L
14211 Fluka Water 1 L
1. Mitchell, J. W. Purification of Analytical Reagents. Talanta, 1982, 29, 993–1002.
The acids, bases, and salts in
the TraceSELECT series have
been developed for sample
preparation and analysis in the
ppb (μg/kg) trace range. Purity
and composition are guaran-
teed with our careful prepara-
tion, testing, and verification of
the final product for metal
content and ionic trace
impurities using ICP-OES, ICP-MS and ion chromatography. To further guaran-
tee purity and stability, TraceSELECT products are packaged in high-quality
containers appropriate for the particular product.
The Sigma-Aldrich Quality Management System guarantees consistent
quality and safety for all TraceSELECTUltra and TraceSELECT products. The
reagents are produced and bottled under clean-room conditions and are
delivered with a Certificate of Analysis.
7sigma-aldrich.com
Table 3. TraceSELECT reagents
Cat. No. Brand Product Name Specification Pack Sizes
45727 Fluka Acetic acid ≥ 99.0% (T) 100 mL, 500 mL
09857 Fluka Ammonium hydroxide solution ≥ 25% in water 100 mL, 500 mL
06454 Fluka Formic acid ≥ 88.0% 250 mL
08256 Fluka Hydrochloric acid ≥ 30% 100 mL, 500 mL
84415 Fluka Hydrochloric acid ≥ 37% fuming (T) 100 mL, 500 mL
47559 Fluka Hydrofluoric acid 47-51% (AT) 100 mL, 500 mL
95321 Fluka Hydrogen peroxide solution ≥ 30% (RT) 100 mL, 500 mL
84385 Fluka Nitric acid > 69.5% (T) 250 mL, 500 mL
77227 Fluka Perchloric acid 67-71% (T) 100 mL, 500 mL, 1 L
79614 Fluka Phosphoric acid ≥ 85% (T) 100 mL, 500 mL
18498 Fluka Phosphorus oxychloride ≥99.9999% 250 mL
30955 Fluka Potassium hydroxide solution ≥ 30% in water (T) 250 mL
13171 Fluka Sodium hydroxide solution ≥ 30% in water (T) 250 mL
84716 Fluka Sulfuric acid ≥ 95% (T) 500 mL
68556 Fluka Tetramethylammonium 25% in H2O 250 mL hydroxide solution
95305 Fluka Water 500 mL, 1 L, 2.5 L, 10 L
Melting digestion is used for solid samples like ores, rock, metals, alloys, ceramic, and
cement, in order to obtain a homogenous residue, which can be dissolved in diluted
TraceSELECT acids. Our TraceSELECT salts obtain a very high purity, with metal traces
typically below 10 μg/kg (10 ppb).
Table 4. TraceSELECT salts
Cat. No. Brand Product Name Specification Pack Sizes
73432 Fluka Ammonium acetate ≥ 99.9999% 100 g
09725 Fluka Ammonium chloride ≥ 99.9995% 25 g, 100 g
09726 Fluka Ammonium phosphate monobasic ≥ 99.9999% 25 g, 100 g
09979 Fluka Ammonium sulfate ≥ 99.9999% 100 g
40581 Fluka Cesium bromide ≥ 99.999% 25 g
90033 Fluka Cesium chloride ≥ 99.9995% 25 g, 100 g
62462 Fluka Lithium carbonate ≥ 99.995% 25 g, 100 g
60348 Fluka Potassium bisulfate ≥ 99.999% 25 g
60111 Fluka Potassium carbonate sesquihydrate ≥ 99.995% 50 g
05257 Fluka Potassium chloride ≥ 99.9995% 25 g, 100 g
60216 Fluka Potassium phosphate monobasic ≥ 99.995% 25 g, 100 g
60371 Fluka Potassium hydroxide hydrate ≥ 99.995% 25 g
60429 Fluka Potassium nitrate ≥ 99.995% 25 g, 100 g
60347 Fluka Potassium phosphate dibasic ≥ 99.999% 100 g
59929 Fluka Sodium acetate ≥ 99.999% 25 g, 100 g
01963 Fluka Sodium bromide ≥ 99.995% 25 g
71347 Fluka Sodium carbonate ≥ 99.9999% 25 g, 100 g
38979 Fluka Sodium chloride ≥ 99.999% 25 g, 100 g
01968 Fluka Sodium hydroxide monohydrate ≥ 99.9995% 25 g, 100 g
71752 Fluka Sodium nitrate ≥ 99.999% 25 g, 100 g
71629 Fluka Sodium phosphate dibasic ≥ 99.999% 100 g
71492 Fluka Sodium phosphate monobasic ≥ 99.999% 25 g, 100 g
8 sigma-aldrich.com/traceselect sigma-aldrich.com/techservice
Reducing Agents for Hydride AAS
In graphite furnace AAS,
element determinations are more
and more often being carried out
with matrix modifiers. Chemical
modification should be considered
if an analyte is highly volatile, or if
the analyte and matrix volatilize at
similar temperatures. Such
modification would allow ashing
at higher (or atomization at lower)
furnace temperatures, resulting in
elimination of the matrix with no
loss of the analyte (or atomization
of the analyte, but not the
matrix). Depending on the
element to be determined, various
substances are used; however,
Trace Analysis: High Purity Reagents Matrix Modifiers
Spectroscopic Buffers for Flame AAS
Table 6. Spectroscopic Buffers for Flame AAS
Cat. No. Brand Product Name Specification Pack Sizes
20980 Fluka Aluminum nitrate cesium Buffer Solution according 500 mL chloride buffer for flame to Schuhknecht and atomic absorption spectrometry Schinkel
20982 Fluka Cesium chloride Lanthanum Buffer solution according 500 mL chloride buffer for flame to Schinkel atomic absorption spectrometry
95164 Fluka Cesium chloride Lanthanum CsCl 100 g/L, LaCl3 250 mL chloride buffer for flame 100 g/L (in water) atomic absorption spectrometry
Table 7. Reducing Agents for Hydride AAS
Cat. No. Brand Product Name Specification Pack Sizes
55459 Fluka Hydroxylamine hydrochloride puriss. p.a., ≥99.0% 50 g, 250 g for AAS
71321 Fluka Sodium borohydride puriss. p.a., ≥96.0% 25 g, 100 g for the determination of hydride formers by AAS
96527 Fluka Tin(II) chloride dihydrate purum p.a., ≥96.0%, 50 g, 250 g Hg ≤0.01 mg/kg
Table 5. Matrix Modifiers
Cat. No. Brand Product Name Specification Pack Sizes
428922 Aldrich Ammonium hydrogenphosphate ~40% (w/v) in H2O 100 mL matrix modifier
428868 Aldrich Calcium matrix modifier 2% Ca in 1 wt. % HNO3 100 mL
95164 Fluka Cesium chloride/Lanthanum CsCl and LaCl3 250 mL chloride matrix modifier 100 g/L each
428884 Aldrich Lanthanum matrix 5% La in 1 wt. % HCl 100 mL modifier solution
63043 Fluka Magnesium matrix modifier puriss. p.a., 10.0 g/L Mg 50 mL in ~17 wt.% HNO3
428906 Aldrich Nickel matrix modifier 5% Ni in 1 wt. % HNO3 100 mL
76040 Fluka Palladium matrix modifier puriss. p.a., 10.0 g/L Pd 50 mL in ~15 wt.% HNO3
palladium nitrate has become one of the most popular. A primary criterion for
such substances is the absence of the element to be analyzed. For this reason, the
recommended reagents indicated below have been specially tested for their
suitability as matrix modifiers.
In flame AAS, spectroscopic
buffers are often used to suppress
physical, ionization, and chemical
interferences. The Schuhknecht
and Schinkel buffer solution, as
used in the determination of alkali
elements, has become particularly
important. A multi-element
standard for the elements lithium,
sodium, and potassium is also
available for this method. The
Schinkel buffer solution enables
the method to be expanded to include up to 14 mono- and divalent elements,
with simple calibration being all that is required for the analysis.
Hydride AAS is used for the
analysis (especially traces) of
arsenic, antimony, tin, selenium,
bismuth, and mercury. It is used
to separate and preconcentrate
analytes from sample matrices by
a reaction that turns them into
their hydride vapors. Sodium
borohydride is the common
reagent of choice for the
reduction. Fluka reagents are specifically analyzed to ensure the absence of
hydride-generating metals.
9sigma-aldrich.com
Solvents for Trace Metal Speciation Analysis
...TraceSELECT solvents for LC-ICP-MS applications
Table 8 TraceSELECT Solvents Ideal for Speciation Analysis
Cat. No. Brand Product Name Specification Pack sizes
01324 Fluka Acetonitrile TraceSELECT (≥99.9%) 1 L
42105 Fluka Methanol TraceSELECT (≥99.9%) 1 L
14211 Fluka Water TraceSELECTUltra 1 L
1. Michalke, B. The coupling of LC to ICP-MS in element speciation; Part II: Recent trends in application. Trends in Analyti-cal Chemistry, 2002, 21(3), 154–165.
2. IUPAC, Pure and Applied Chemistry, 2000, 72, 1453–1470.
The toxicity of trace metals in
food, clinical chemistry, biology,
and environmental sciences is an
area of increasing interest. In the
environment, many diverse
species of an element can be
present, and different species of
the same element can possess
very different degrees of toxicity.
Monitoring elemental species
requires an analytical method that
is sensitive and specific enough to
resolve and quantify the individual
species at ultra-trace levels, as an
individual toxic species may consti-
tute only a fraction of an ele-
ment’s total concentration in a
sample. The coupling of the two
well-established analytical
techniques, HPLC and inductively
coupled plasma-mass spectrom-
etry (ICP-MS), is straightforward
primarily because the flow rates
commonly used with LC are
compatible to conventional liquid
sample introduction systems, such
as those based on pneumatic
nebulization. Thus, the outlet of
the LC column is directly con-
nected to the ICP-MS nebulizer.
This technique is especially useful
in carrying out automated
high-throughput speciation
analysis. International trends show
speciation of metals as an area of
very high research interest. In the
future, speciation of biological
samples will undoubtedly involve
determinations of which organic
molecules attract which metals in
specific sample types.
ICP-MS is a superior
detection technique for trace
elements in general, but
especially for elements of
interest such as arsenic, selenium, cadmium, iodine, and others in chromato-
graphic eluents.
Sigma-Aldrich has recently developed new high purity TraceSELECT solvents for
speciation analysis by LC-ICP-MS. TraceSELECT solvents undergo rigorous
purification procedures followed by UV spectroscopy, IC, and ICP-MS testing to
assure high chemical purity and high UV transmittance. The blank values for
metal traces in these solvents are in the ppb range or lower.
Definition of speciation analysis
The International Union of Pure and Applied Chemistry (IUPAC) defines
speciation analysis as the “analytical activities of identifying and/or measuring the
quantities of one or more individual chemical species in a sample.” A chemical
species is a “specific form of an element defined as to isotopic composition,
electronic or oxidation state, and/or complex or molecular structure.”
In speciation analysis, the objective is usually to determine the identity and/or
concentration of one or more chemical species in a sample, often of natural origin
and therefore potentially containing many different species. Care must be taken
to choose and execute the analysis to maximize sensitivity and specificity.
Performing a speciation analysis in a complex mixture involves separation,
identification, and characterization of various forms of elements in the sample.
The most commonly used strategy for speciation analysis is to perform a separa-
tion step before a generic detector.
LC separation coupled with ICP-MS
The hyphenated technique HPLC-ICP-MS is a robust, sensitive element-selective
method capable of giving a complete picture of the elemental species in a
solution. The elemental response is usually independent of species, so it is often
possible to quantify a species even when its structure is unknown (assuming good
HPLC recovery). Identification, however, is based solely on retention time
matching; hence, a compound in the sample can be identified only by comparison
with a standard.
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8Min
10 sigma-aldrich.com/traceselect sigma-aldrich.com/techservice
Certified Eluent Concentrates and High Purity Water for Ion Chromatography
Table 9. Certified Eluent Concentrates and High Purity Water for Ion Chromatography from Sigma-Aldrich
Cat. No. Brand Product Name Specification Pack Sizes1
50972 Fluka 2,6-Pyridinedicarboxylic for IC, 0.02 M in water 1 L acid solution
50433 Fluka DL-Tartaric acid solution for IC, 0.1 M in water 1 L
55517 Fluka Methanesulfonic acid solution for IC, 0.1 M in water 1 L
16355 Fluka Nitric acid solution for IC, 0.1 M in water 1 L
68487 Fluka Oxalic acid solution for IC, 0.1 M in water 1 L
50439 Fluka Perchloric acid solution for IC, 0.01 M in water 1 L
61699 Fluka Potassium hydroxide solution for IC, 0.1 M in water 1 L
36486 Fluka Sodium bicarbonate solution for IC, 0.1 M in water 1 L
56169 Fluka Sodium carbonate solution for IC, 0.1 M in water 1 L
43617 Fluka Sodium hydroxide solution for IC, 0.1 M in water 1 L
68279 Fluka Sulfuric acid solution for IC, 0.1 M in water 1 L
00612 Fluka Water for IC2 2.5 L, 5 L
1 Packaging: HDPE bottles with 45 mm screw-thread cap 2 can also be used for voltammetry
Ion chromatography (IC) is an
analytical technique that is used to
separate and quantify ppm-levels of
common anions (e.g. fluoride,
chloride, nitrite, nitrate, and sufate)
and cations (e.g. ammonium, and
alkali- and earth alkali ions) in
aqueous samples. Separation occurs
via differential interaction with an
ion-exchange resin. Conductivity is
the most common detection
method. The sensitivity of IC makes
it ideal for low ppm level quantifica-
tion and also for trace analysis; thus
IC itself creates the requirement for
high purity eluents and well-defined
standards. As a leading supplier of
high-quality products for all areas of
analytical chemistry, Sigma-Aldrich
has expertise in the production of
standards, eluents, and high purity
water suitable for sensitive ion
determination.
Designed to save IC analysts’ time and to ensure the most sensitive and reproducible
IC determinations, our lines of TraceCERT standards for IC and pre-made Certified
Eluent Concentrates for IC are convenient time and cost-saving options.
The Certified Eluent Concentrates, listed in Table 9, are traceable by potentiometric
titration to NIST Standard Reference Materials and certified in accordance with ISO
Guide 31. All details regarding exact content, uncertainty, traceability, and expiration
date are described in the Certificate of Analysis, which is available electronically on our
Web site: sigma-aldrich.com/IC
To meet your needs for IC analysis, we also offer certified multi-element standards
(PRIMUS) and a new test kit for IQ, OQ, or PQ (Fluka 12674) activities.
Ultra Pure Reagents for VoltammetryTraceSELECT reagents for ultra-trace analysis and metal speciation
Voltammetry is predominantly
used for inorganic trace analysis of
anions and cations, but can also be
used for the determination of
various organic compounds. The
most important fields of application
of inorganic determinations are in
metallurgy, environmental analysis,
food analysis, toxicology, and
clinical analysis. This technique is
also a preferred method for the
determination of certain metal
speciations, such as Fe(II)/Fe(III)
or Cr(III)/Cr(VI).
When mercury is used as an
electrode in a voltammetric cell,
the technique is called polarography. The reduction of metals
into mercury is more favourable than reduction to the solid-
state electrode. Further on there is always a clean new Hg
electrode surface available for each measurement.
Sigma-Aldrich has recently introduced an ultra pure mercury
quality suitable for trace analysis by polarography and three
buffers substances specifically designed for voltammetry and ion
chromatography.
Table 10. High Purity Reagents for Voltammetry*
Cat. No. Brand Product Name Specification Pack sizes
83359 Fluka Mercury for polarography ≥ 99.9995% 5 g, 100 g
94068 Fluka Citric acid monohydrate TraceSELECT 100 g
05878 Fluka L-Ascorbic acid TraceSELECT 100 g
93722 Fluka Oxalic acid dihydrate TraceSELECT 100 g
* Further reagents used for voltammetry are listed in Tables 3 and 4.
1. Henze, G.. Introduction to Polarography and Voltammetry, Metrohm Monograph 60 pages, DIN A 5 format. For a free copy, please contact www.metrohm.com
Multi-mode Electrode (MME)Published with kind permission of Metrohm AG, Switzerland
11sigma-aldrich.com
Calibration for Trace Analysis:TraceCERT - Certified Reference Materials
Following long-lasting coopera-
tion with different metrological
institutes, such as Switzerland’s
EMPA and Germany’s BAM,
Sigma-Aldrich has built-up a
broad knowledge base in the field
of certified reference material
(CRM) production. After two
years of continuous development,
our Buchs facility was ready to be
audited by the Swiss Accreditation
Service and received the highest
achievable quality assurance level
for CRM producers: the double
accreditation as both a testing
laboratory (ISO/IEC 17025) and a
CRM producer (ISO Guide 34).
This combination is also called the
“Gold Standard” accreditation for
CRM producers.
The quality of a CRM strongly depends on the quality of the starting materials
and, therefore, their characterization is very important. TraceCERT starting
materials are characterized by two different approaches: the direct measurement
of the purity by the most accurate method (e.g. titrimetry or high-performance
ICP-OES) and the purity assignment by the “100% minus impurities” approach.
The combination of these two purity assignments leads to two independent
traceability chains, and results in higher reliability of the CRM.
The first products developed and produced under these doubly-accredited
conditions are our TraceCERT calibration standards for spectrometry and ion
chromatography. The name TraceCERT stands for Traceability and CERTified, and
means that these CRMs are suitable for even the most challenging analytical
applications. They also fulfill all the needs of our customers who work in regu-
lated environments.
Key characteristics of these new CRMs are: l Unique level of accuracy and lot-specific values l Produced in doubly-accredited laboratory that fulfills ISO/IEC 17025
and ISO Guide 34 l Traceable to at least two independent references (NIST, BAM or SI unit kg) l Comprehensive documentation according to ISO Guide 31, including
proper uncertainty calculation l Expiration date and storage information l Sophisticated packaging l Competitively priced
More information on issues
related to CRM quality and
production can be obtained by
reading the series of Analytix
articles published in 2006 and
2007: Part 1, Vol. 5 (2006) and
Part 2-5: Vol. 1-4 (2007),
available at sigma-aldrich.com/
analytix. This series covered the
following topics: traceability,
uncertainty, characterization of
high-purity starting materials,
production, packaging and
stability studies.
Visit our Web site on a regular basis, as
we are constantly adding new TraceCERT Standards:
sigma-aldrich.com/tracecert
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