Negative ion mobility spectrometry for selected inorganic pollutant gases and gas mixtures in air

Abstract

4) Alcock. N. J.; Corbelli, L.; Games, D. E.; Lant, M. S.; Westwood, S. A.Spectra for inorganic gases common to combustion emisdons were obtained in air by using negative ion mobility spectrometry (NIMS). Gases were characterized individuaiiy from 10 to over 4000 ppb in alr and in two binary mixtures of S02/N02 and HCI/SOP. Spectra for HCI and SO2 were distinguished by single Intense peaks at reduced mobilities ( K O ) of 2.98 cm2/(V 8 ) and 2.30 cm2/(V s), respectively. The product ion for NO, had a KO of 2.80 cm2/(V 8 ) as determined using binary mixture studies and was unresolved otherwise from reactant Ions. I n contrast, NIMS spectra for H2S showed three peaks that were concentration dependent and had mobility values of 2.38, 2.28, and 1.70 cm2/(V 8 ) . Peak currents for H2S ranged from 10 to 50 pA and the estimated limit of detection (LOD) was 10 ppb. Peak currents for SO2 ranged from 15 to 65 pA and the estlmated LOD was 2 ppb. The range of peak currents for HCI was comparatively large at 140-215 pA and estimated LOD was <1 ppb. At constant concentration for HCI at 60 ppb, SO2 was added from 100 to 900 ppb. Competitive Ionization was observed in the order Of HCI > NO2 > SOP

New Highly Stable Metallabenzenes via Nucleophilic Aromatic Substitution Reaction

“…The theory of drift tube IMS has been described in detail previously 1–3. IMS is a powerful tool in different areas, such as the monitoring of environmental pollutants,4–6 warfare agents,7 explosives,8–10 herbicides,11 pesticides,12, 13 petroleum products,14 and illicit/legal drugs 15. In addition, it is also used in peptide analysis16, 17 and space exploration 18.…”

“…Negative reactant ions formed in radioactive ionization in IMS were first studied during the 1970s19, 20 and then later using a plasma ionization or corona discharge ion source 21–23. The negative ion mode with radioactive ionization has been used, for example, to measure inorganic pollutant gases, such as SO 2 , H 2 S, HCl, and NO 2 ,6 anesthetics24 and organic nitrogen compounds such as 2,4,6‐trinitrotoluene (2,4,6‐TNT)8, 9, 25 and chlorinated compounds such as 2,4‐dichlorophenoxyacetic acid and 2,4‐dichlorophenol 26. Explosives and chemical warfare agents (e.g.…”

Photoionization in air with ion mobility spectrometry using a hydrogen discharge lamp

“…Ion mobility spectrometry (IMS) has been used in the separation and detection of organic (1)(2)(3)(4)(5) and inorganic (6,7) compounds in the gas phase at atmospheric pressure. Separation is achieved through differences in gaseous mobility of molecular or pseudomolecular ions under the influence of an applied electric field and against the flow of a neutral drift gas.…”

“…Historically, the most common ionization method in IMS has been chemical ionization (Cl) initiated with reactant ions formed from ß emission. While Cl provided high sensitivity (sub-part-per-billion levels) and some selectivity in ionization processes, working ranges of analyte response vs. concentration were only 10-100. Selectivity of ionization in mixtures was quantitatively shown recently to be governed in CI-IMS by proton affinities in the positive mode (5) and electron affinities in the negative mode (6). Unfortunately, selectivity of ionization was controlled mostly by molecular parameters, rather than by the analyst, except for the choice of reagent gas.…”

Real-time reaction monitoring using ion mobility-mass spectrometry

“…8 IM has evolved into a technique for sensitive detection of many trace compounds and a wide range of chemical species such as chemical warfare agents, 9 biomolecules, 10 drugs of abuse 11 and inorganic substances. 12 IM has also been reported for the online monitoring of monomer concentrations in (semi-)batch emulsion polymerisation reactors, 13 the monitoring of yeast fermentation, 14 part per billion level process monitoring of ammonia in process streams 15 thus indicating the potential of IM as a rapid and precise measurement device for the monitoring of processes. More recently IM has been reported in pharmaceutical applications ranging from cleaning verification of manufacturing equipment, 16 direct formulation analysis [17][18][19] and protection of pharmaceutical workers health and safety.…”