[Determination of moth-proof agent residues in textiles with headspace solid-phase microextraction and gas...

A procedure is described for the identification and determination of volatile moth-proof pesticide residues, dichlorobenzene and naphthalene, in textile products by headspace solid-phase microextraction (HS-SPME) coupled with GC/MS in selective ion monitoring mode (SIM). Several standard fabrics (ISO 105/F01-1982) are used as sample matrices to reduce the target compound-matrix interaction. Prior to SPME, 0.2 g textile sample is immersed in 3 mL boric acid-citric acid-sodium acid phosphate buffer (pH 2.2) solution with 300 g/L sodium chloride and 5% (volume fraction) methanol for supersonic treatment in water bath(50 +/- 1) degrees C. Then an SPME fiber holder is used manually by passing the needle through the septum of the sample vial, depressing the plunger and lowering a fused silica fiber coated with 100 microns polydimethylsiloxane (PDMS) into the headspace right above the sample solution. Adsorption equilibrium is almost established within 5 minutes with magnetic stirring at (40 +/- 1) degrees C. After sample adsorption, draw SPME fiber into the needle, and withdraw the needle from the sample vial and immediately introduce it into the chromatograph injector, where the adsorbed analytes are thermally desorbed for 3 minutes at 230 degrees C and delivered to a capillary GC column for analysis by mass detector. The method provides data of very good linearity with low coefficients of variation for volatile target compounds like p-dichlorobenzene and naphthalene. For all the fabrics tested, typical limits of detection (LOD) were 1 microgram/kg and average recoveries from fortified sample fabrics were between 83.6%-115.2% and the relative standard deviations of the residues were 8.1%-9.8%.