Determination of organochlorine pesticides and their metabolites in radish after headspace solid-phase microextraction using calix[4]arene fiber.

A novel laboratory-made sol-gel calix[4]arene/hydroxy-terminated silicone oil coated fiber has been applied for headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) with electron capture detection (ECD) to determine 12 organochlorine pesticides (OCPs) and their metabolites in radish sample. The analytes in the study consisted of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (BHC), 1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane (o,p'-DDT), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT), 2,4-dichlorobenzophenone (o,p'-DBP), 4,4-dichlorobenzophenone (p,p'-DBP), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE), bis(4-chlorophenyl)methane (p,p'-DDM), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDD) and endrin. The following parameters were adjusted to optimize HS-SPME in order to obtain the maximum sensitivity: extraction temperature, extraction time, the addition of salt, desorption temperature and time. Especially, the effect of the complex radish matrix on quantitative extraction of pesticides was discussed in detail. Detection limits of the developed method for radish matrices were below 174ng/kg for all pesticides. Relative standard deviations for quintuplicate analyses of radish samples fortified each analytes were not higher than 13.1%. The results demonstrate the suitability of the HS-SPME/GC-ECD approach for the analysis of multi-residue OCPs and metabolites in radish.