Ultraviolet photolytic vapor generation from particulate ensembles for detection of malathion residues in aerosols

A method to selectively generate vapor signatures from malathion entrained within matrices of surface-impacted aerosol particles has been demonstrated. The method uses ultraviolet radiation (172 or 222 nm) from a continuous wave discharge lamp to photodissociate malathion molecules collected within...

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Bibliographic Details
Published in:	Analytica chimica acta Vol. 531; no. 2; pp. 267 - 277
Main Authors:	Kunz, Roderick R., Leibowitz, Frank L., Downs, Deanna K.
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 01-02-2005 Elsevier
Subjects:	Aerosol Analytical chemistry Bacillus globigii Chemistry Exact sciences and technology Ion mobility spectrometry Malathion Organophosphates Photolysis Spectrometric and optical methods Vacuum ultraviolet Vacuum ultraviolet Malathion Ion mobility spectrometry Photolysis Aerosol Organophosphates Pyrolysis Instrumentation Ultraviolet photolysis Vaporization Particle detection Sensitivity Ion mobility Residue Aerosols Ion spectrometry Organophosphorus compounds Vacuum ultraviolet: Photolysis
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Summary:	A method to selectively generate vapor signatures from malathion entrained within matrices of surface-impacted aerosol particles has been demonstrated. The method uses ultraviolet radiation (172 or 222 nm) from a continuous wave discharge lamp to photodissociate malathion molecules collected within and on surface-impacted particles, followed by detection via ion mobility spectrometry (IMS). Since surface heating does not occur, only those molecules whose photofragments exhibit high vapor pressure are introduced into the IMS instrument and then only those exhibiting high proton affinity are subsequently detected. This process produces less signal clutter than in pyrolysis-IMS, where the background aerosol is pyrolyzed along with the sample. Quantities of malathion as small as 50 ng could be detected when the malathion was entrained on a clean surface, and as small as 100 ng when co-entrained on a surface with much larger quantities of background aerosols such as diesel soot, road dust, Bacillus globigii, albumin, and cotton lint. This sensitivity indicates that, when combined with a particle collector as an effective pre-concentrator, detection of malathion aerosol concentrations of <0.01 mg/m 3 will be possible. Since malathion can be viewed as a model compound, this technique is also extendable to the detection of organophosphate war chemicals.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1
ISSN:	0003-2670 1873-4324
DOI:	10.1016/j.aca.2004.10.085