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 (alpha-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.
da Silva
Rogério Cesar
RC
ThoMSon Mass Spectrometry laboratory, Institute of Chemistry, State University of Campinas, 13084-971 Campinas, SP, Brazil.
Zuin
Vânia Gomes
VG
Yariwake
Janete Harumi
JH
Eberlin
Marcos Nogueira
MN
Augusto
Fabio
F
D004129:Dimethylpolysiloxanes; D004340:Drug Contamination; D006843:Hydrocarbons, Chlorinated / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods*; D009943:Organophosphorus Compounds / Q000032:analysis; D029598:Passiflora / Q000737:chemistry; D010575:Pesticides / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis*; D011142:Polyvinyl Alcohol; D052617:Solid Phase Microextraction / Q000379:methods*
D004129:Dimethylpolysiloxanes; D006843:Hydrocarbons, Chlorinated; D009943:Organophosphorus Compounds; D010575:Pesticides; D010936:Plant Extracts; D011142:Polyvinyl Alcohol