Validation of an HS-SPME-GC-MS method for the analysis of multiple fumigants in low moisture agricultural commodities

A single method for the analysis of multiple fuimgant residues in low moisture commodity is presented. HS-SPME-GC-MS is used to detect the preplant and postharvest fumigants SF, EF, MB, EtO, PPO, EF, MITC and 1,3-D, along with their degradants PCH, PBH, ECH, EBH, and EtOH. Nearly all of the analytes are detected with detection limits below 0.010 mg kg^-1 and with 0.02 mg kg^-1 limits of quantitation. Likewise, recoveries of the analytes from fortified walnut and rice samples were all between 70 and 120% accuracy with RSDs below 20%, with only minor exceptions. Good linearities were obtained over the concentration range of 7-235 ng g^-1 with correlation coefficients over 0.990. Derivatization of PPO and EtO with iodide salt, prevented their degradation during the analysis. The method is quick, produces little waste and is shown to be sensitive and accurate.