Analysis of pyraclofos in crops by the Swedish National Food Administration gas chromatographic multiresidue methodology

The National Food Administration (NFA) gas chromatographic (GC) multiresidue method was assessed to determine residues of pyraclofos in fruits and vegetables. The relative retention times of pyraclofos in the FPD/OV-1701 and TSD/SE-30 detector/column systems used for GC analysis (using parathion as reference) were 2.11 and 2.04, respectively. The corresponding relative response factors were 0.34 and 0.40. The mass spectrum obtained for pyraclofos using a MSD/PAS1701 GC system suggests the use of the peaks at mit 360 (molecular and base peak), 194 and 139 to confirm trace levels of pyraclofos by gas chromatography with mass selective detection (GC/MSD) in SIM mode. Recovery values obtained with the complete NFA/GC multiresidue method for pyraclofos from tomato and strawberry samples spiked at levels of 0.05 or O.40mg/kg ranged from 72% to 111%. The Limit of quantification of pyraclofos was stated as O.O5mg/kg, but levels of 0.02mg/kg could be determined from the TSD/SE-30 chromatographic response. The elution profile of pyraclofos on a GPC/SX-3 Biobeads column was also determined in this work.