Examination of Ionization Efficiency of Silyl Compounds Using a Flowing Afterglow

Breath analysis is a noninvasive diagnostic technique used to detect several human deficiencies and diseases. Increased concentrations of particular volatile organic compounds (VOCs) are observed in individuals with problems such as acute myocardial infarction,1 rheumatoid arthritis,1 vitamin E deficiencies,1 and schizophrenia.2 Analysis of VOC composition can be completed by studying gas phase ion reactions in a Flowing Afterglow (FA) instrument. This study focused on the utility of a silyl compound as a precursor ion in the FA as well as its reactivity with hydrocarbons. The reactivity of the ion is important because it will aid in the identification and quantification of hydrocarbons. Other studies performed on the FA have investigated the efficacy of silyl compounds as ion precursors because of their proton-like properties and reactivity. In this study three different silyl compounds were evaluated for their usefulness as an ion source: tetramethylsilane, hexamethyldisilane, and hexamethyldisiloxane. Following ionization, various neutral reagents were introduced into the instrument to characterize the reactions of these ions both qualitatively and quantitatively