SUPERCRITICAL-FLUID EXTRACTION AND GAS-CHROMATOGRAPHY ION-TRAP MASS-SPECTROMETRY OF PENTACHLORONITROBENZENE PESTICIDES IN VEGETABLES

An analytical approach using supercritical fluid extraction (SFE) foll owed by gas chromatography/ion trap mass spectrometry (GC/ITMS) was de veloped for the analysis of the fungicide pentachloronitrobenzene and several analogues in vegetables, The method was tested in the analysis of carrots, potatoes, green beans, celery, and radishes fortified wit h pentachloronitrobenzene, tetrachloronitrobenzene, pentachloroanisole , pentachlorothioanisole, pentachlorobenzene, hexachlorobenzene, and p entachloroaniline, An incurred carrot sample analyzed by the method wa s shown to contain hexachlorobenzene at 7 +/- 3 ng/g, which agreed wit h the concentration (8 +/- 4 ng/g) determined using a traditional solv ent-based method, The SFE method consisted of the following steps: (1) homogenizing a 50 g vegetable sample and weighing a 3 g subsample; (2 ) mixing 2 g sorbent (Hydromatrix) with the subsample to absorb moistu re and packing a 10 mL extraction vessel; (3) extracting with 40 mL CO 2 at 200 atm, 40 degrees C, and a flow rate of 3 mL/min; and (4) colle cting the extract on a 1 g alumina basic trap at 25 degrees C and flus hing with 8 mL isooctane. Collection of the extract on alumina efficie ntly removed chlorophyll and other matrix interferences, GC/ITMS in th e electron-impact mode confirmed and quantitated the analytes at conce ntrations as low as 1 ng/g.