Gas chromatography double focusing sector-field ICP-MS as an innovative tool for bad breath research

The development of a new methodology for the determination of volatile sulf ur compounds (VSCs) in human breath by gas chromatography (GC) coupled to I CP-double focusing (DF)-MS is described. The coupling between GC and ICP-DF -MS was achieved by means of an interface built in our laboratory. The diff erent parameters affecting the chromatographic separation and the sulfur-sp ecific detection by ICP-DF-MS were optimised in order to achieve best respo nse for the isotope S-32. Selected chromatographic conditions are given usi ng a capillary column for sulfur Compounds (SPB-1 Sulfur). The effect Of us ing cold plasma conditions and a shielded torch. available in the double fo cusing instrument, were also evaluated to obtain the best analytical perfor mance characteristics for S-32 monitoring. Using the selected instrumental conditions for this GC-ICP-DF-MS system, it was possible to obtain detectio n limits between 8 and 33 ppb (v/v), depending upon the Sulfur chemical spe cies. and precisions of around +/- 7.5% at 800 ppb (v/v) levels. The develo ped hybrid method was successfully applied to the determination of volatile sulfur compounds in the head-space of dials containing human saliva. The s aliva is incubated in anaerobic conditions at 37 C in order to reproduce th e rotting processes, that are caused in the mouth by anaerobic microbiota, and which are responsible for more than 80% of bad breath cases described i n the literature.