B . Keerthana,B.Pharm,

s.p.s.p

DART Ion source-Mass spectrometry

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Contents:• Introduction

• Basic principle of Mass spectrometry

• Ionization

• Ion sources

• DART ion source

• DART ion application

• Mass spectrometry analyzers and detectors

• References.

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Introduction of Mass spectrometry• MASS SPECTROMETRY:

Mass spectrometry is an instrumental technique in which sample is converted to rapidly moving positive ions by electron bombardment and charged particles are separated according to their masses.

• MASS SPECTRUM:

Mass spectrum is a plot relative abundance against the ratio of mass/charge(m/e).

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Simple mass spectrometry

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Organic molecules are bombarded with electrons

Converted into high energetic positively charged ions(molecular ions or parent ions)

• Further break up into smaller ions(fragment ions or daughter ions)• The formed ions are separated by deflection in magnetic field according

to their mass and charge.

MASS SPECTRUM

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Basic principle:

Modern Mass spectrometry Inlet system Ion sources Mass analysers Ion detectors Vacuum system.

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Instrumentation of mass spectrometry

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Ionization sources: Chemical Ionization (CI) Atmospheric Pressure chemical ionization(APCI) Electron Impact (EI) Electrospray Ionization(ESI) Fast Atom Bombardment (FAB) Field Desorption/Field Ionization (FD/FI) Matrix Assisted Laser Desorption Ionization(MALDI) Thermo spray Ionization (TI) Direct analysis in real time(DART) Slide 8

Electron ionization:• Side view of EI • Ion formation reaction occur

in EI

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Chemical Ionisation (CI) The ion formation reactions that can occur during methane

CI.

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Electrospray ionisation (ESI):• An ESI source

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• The mechanism of ion formation in ESI.

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Atmospheric Pressure Chemical Ionisation (APCI):

detailed view of the mechanism of APCI.

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Fast atom bombardment(fab)& liquid secondary ion mass spectrometry(lSIMS):

the mechanism of fast particle beam ionisation mass spectrometry (FAB and LSIMS)

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Matrix-assisted Laser Desorption/Ionisation (MALDI)

diagram of the mechanism of MALDI.

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Introduction:The new ion source reported herein over-comes these limitations. The new technique, referred to as Direct Analysis in Real Time (DART

tm), has been coupled to the AccuTOFLCtm atmospheric pressure ionization mass spectrometer to permit high-resolution, exact mass measurements of gases, liquids, and solids.

DART successfully sampled hundreds of chemicals, including chemical agents and their signatures, pharmaceutics, metabolites, pesticides and environmentally significant compounds etc.,

The composition of drug capsules and tablets was directly analyzed.Slide 16

DART IONSOURCE ( DIRECT ANALYSIS IN REAL TIME ) :

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Dart ion source-mass spectrometry:

Background and Principle of Operation: The discovery that DART could be used for positive-ion and negative-

ion non-contact detection of materials on surfaces, as well as for detection of gases and liquids.

DART is based on the atmospheric pressure interactions of long-lived electronic excited-state atoms or vibronic excited-state molecules with the sample and atmospheric gases.

o The DART ion source is shown. A gas (typically helium or nitrogen) flows through a chamber where an electrical discharge produces ions, electrons, and excited-state (metastable) atoms and molecules.

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Principle of DART Ionization:DART ionization is based on the interaction between excited state atoms or molecules, andatmospheric gas and/or analytes. Plasma is generated by glow discharge from the needle electrode in a helium gasstream. The plasma includes ions, electrons, and excited state (metastable) atoms ormolecules. The majority of charged particles are eliminated by the groundedelectrode and the excited state neutral species are expelled to the atmosphere.The gas stream can be heated by the gas heater to help analytes vaporization or desorptionfrom the substrate surface.

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DART Advantages Minimal sample preparation; Sample maintenance under ambient conditions Outside the vacuum system; Rapid Sensitive High‐throughput analysis; The ability for in‐situ detection. Gentle ionization methods. Used for both organic and biological. Compounds, polar and non‐polar molecules Slide 20

Dart applications: Forensics Pharmaceutics food chemistry biological samples chemical analysis fragrance industry DART has been used for analysis of explosives ,drugs ,

inks , sexual assault evidence , and of synthetic cannabinoids in herbal samples.

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Mass Analyzers: quadrupoles Time-of-Flight (TOF) magnetic sectors Fourier transform and quadrupole ion traps.

Mass detectors: Electron multiplier Faraday cup Scintillator ('Daly' detector). Slide 22

fields that use mass spectrometry:Pharmaceutical sciencesProteomicsDrug discoveryClinical testingGenomicsEnvironmental sciencesGeology etc.,

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Applications of mass spectrometer:

[1]. https://masspec.scripps.edu/.[2].Merriam-Webster dictionary, Medical dictionary by FARLAX, https://en.Wikipedia.org/.[3]. Modern Mass Spectroscopy, pp. 1-302, 225. Springer-Verlag, Berlin, 2003.[4]. MacMillan Group Meeting 2005 Sandra Lee.[5]. http://simons.com/.[6].RAPID COMM MASS SPECTROM,vol-II,2-16(1997),[7].JEOL USA,Inc. EAI Corporation, GEO Centers Inc. Edgewood chemicalBiological center.[8].https://www.jeolusa.com/ms/ms prodsaccutof_dart.html.[9].Eid Alsbou (2010), MEMORIAL UNIVERSITY.[10]. Witt & Bowers: JACS 2000,122, 3458.[11]. J.L. Jimenez – Fall 2007 University of Colorado-Boulder.

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References:

Thank you