Fiber introduction mass spectrometry: determination of pesticides in herbal infusions using a novel sol–gel PDMS/PVA fiber for solid‐phase microextraction

An application of the direct coupling of solid‐phase microextraction (SPME) with mass spectrometry (MS), a technique known as fiber introduction mass spectrometry (FIMS), is described to determine organochlorine (OCP) and organophosphorus (OPP) pesticides in herbal infusions of Passiflora L. A new fiber coated with a composite of poly(dimethylsiloxane) and poly(vinyl alcohol) (PDMS/PVA) was used. Sensitive, selective, simple and simultaneous quantification of several OCP and OPP was achieved by monitoring diagnostic fragment ions of m / z 266 (chlorothalonil), m / z 195 (α‐endosulfan), m / z 278 (fenthion), m / z 263 (methyl parathion) and m / z 173 (malathion). Simple headspace SPME extraction (25 min) and fast FIMS detection (less than 40 s) of OCP and OPP from a highly complex herbal matrix provided good linearity with correlation coefficients of 0.991–0.999 for concentrations ranging from 10 to 140 ng ml −1 of each compound. Good accuracy (80 to 110%), precision (0.6–14.9%) and low limits of detection (0.3–3.9 ng ml −1 ) were also obtained. Even after 400 desorption cycles inside the ionization source of the mass spectrometer, no visible degradation of the novel PDMS/PVA fiber was detected, confirming its suitability for FIMS. Fast ( ca 20 s) pesticide desorption occurs for the PDMS/PVA fiber owing to the small thickness of the film and its reduced water sorption. Copyright © 2007 John Wiley & Sons, Ltd.