title: Ketalization of phosphonium ions by 1,4-dioxane: selective detection of the chemical warfare agent simulant DMMP in mixtures using ion/molecule reactions.
abstract: Phosphonium ions CH(3)P(O)OCH(3)(+) (93 Th) and CH(3)OP(O)OCH(3)(+) (109 Th) react with 1,4-dioxane to form unique cyclic ketalization products, 1,3,2-dioxaphospholanium ions. By contrast, a variety of other types of ions having multiple bonds, including the acylium ions CH(3)CO(+) (43 Th), CH(3)OCO(+) (59 Th), (CH(3))(2)NCO(+) (72 Th), and PhCO(+) (105 Th), the iminium ion H(2)C[double bond]NHC(2)H(5)(+) (58 Th) and the carbosulfonium ion H(2)C[double bond]SC(2)H(5)(+) (75 Th) do not react with 1,4-dioxane under the same conditions. The characteristic ketalization reaction can also be observed when CH(3)P(OH)(OCH(3))(2)(+), viz. protonated dimethyl methylphosphonate (DMMP), collides with 1,4-dioxane, as a result of fragmentation to yield the reactive phosphonium ion CH(3)P(O)OCH(3)(+) (93 Th). This novel ion/molecule reaction is highly selective to phosphonium ions and can be applied to identify DMMP selectively in the presence of ketone, ester, and amide compounds using a neutral gain MS/MS scan. This method of DMMP analysis can be applied to aqueous solutions using electrospray ionization; it shows a detection limit in the low ppb range and a linear response over the range 10 to 500 ppb.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Xubin
authors.initials: X
authors.lastname: Zheng
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D002619:Chemical Warfare Agents / Q000032:analysis* / Q000737:chemistry*; D004146:Dioxanes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D013058:Mass Spectrometry; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000032:analysis* / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D002619:Chemical Warfare Agents; D004146:Dioxanes; D007477:Ions; D009943:Organophosphorus Compounds; C031116:dimethyl methylphosphonate; C025223:1,4-dioxane