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A Practical Guide on Coupling a Scanning Mobility Sizer and Inductively Coupled Plasma Mass Spectrometer (SMPS-ICPMS)
Published on: July 11, 2017
Miniature differential mobility spectrometry using atmospheric pressure photoionization
Erkinjon G Nazarov1, Raanan A Miller, Gary A Eiceman
1Sionex Corporation, 8-A Preston Court, Bedford, Massachusetts 01730, USA. Egnazrov@sionex.com
Analytical Chemistry
|July 1, 2006
Summary
A miniature differential mobility spectrometer with photoionization effectively detects compounds at sub ppm(v) levels. This technique shows promise as a viable alternative to traditional radioactive sources for ion detection.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Environmental Science
Background:
- Differential mobility spectrometry (DMS) is a powerful analytical technique for separating and detecting ions.
- Traditional DMS often utilizes radioactive 63Ni sources for ionization, posing safety and regulatory concerns.
- Photoionization offers a potentially safer and more versatile alternative for generating ions in DMS.
Purpose of the Study:
- To investigate the performance of a miniature differential mobility spectrometer equipped with a photoionization source.
- To evaluate the effectiveness of photoionization for detecting various organic compounds and inorganic ions.
- To compare photoionization with traditional radioactive sources for ion generation in DMS.
Main Methods:
- A miniature differential mobility spectrometer was coupled with a photoionization source operating at atmospheric pressure.
- Positive and negative ion spectra were obtained using various dopants (benzene, acetone) and analytes (aromatic hydrocarbons, dimethyl methylphosphonate, butanone, sulfur hexafluoride, nitrogen dioxide).
- Gas chromatography was used in conjunction with DMS for the analysis of aromatic hydrocarbon mixtures.
Main Results:
- Protonated molecular ions and dimer ions were successfully generated using benzene as a dopant.
- Detection of aromatic hydrocarbons showed dependence on moisture levels, forming molecular ions or hydrated protons.
- Negative ions were detected via electron capture, and nitrate ions were formed with nonlinear concentration dependence.
- Dopants enhanced ion formation by up to two orders of magnitude, achieving sub ppm(v) detection limits.
- Photoionization demonstrated comparable or superior performance to radioactive sources.
Conclusions:
- Photoionization is a highly effective ionization method for miniature differential mobility spectrometry.
- The system achieves sensitive detection of various compounds at trace levels (sub ppm(v)).
- Photoionization presents a strong case as a safer and versatile alternative to radioactive ionization sources in DMS.
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