Analysis of phenothrin and its metabolite 3-phenoxybenzoic acid (PBA) in agricultural products by GC and ion-trap GC/MS

Abstract

A sensitive method for analysis of phenotrin and its metabolite 3-phenoxybenzoic acid (PBA) in agricultural products by gas chromatography with electron capture detection (ECD-GC) and ion-trap gas chromatography/mass spectrometry (GC/MS) with chemical ionization (CI) was investigated. After phenotrin in vegetables, fruits, potatoes, starches, and tea had been extracted with acetone, or in cereals and beans had been extracted with acetonitrile followed by Florisil column chromatography, it was reextracted into n-hexane. PBA was determined by ECD-GC after esterification with hexafluoroisopropyl alcohol (HFIP) and diisopropylcarbodiimide (DIC). Phenothrin was determined by monitoring its molecular ion peak using ion-trap GC/MS and was confirmed by observing its spectral pattern. The detection limit for phenothrin by ECD-GC and ion-trap GC/MS by this method was 0.01 ppm. The detection limit for PBA by ECD-GC was 0.001 ppm. When phenothrin and PBA were added to samples at 0.2 and 1.0 ppm, the recoveries of phenothrin in each agricultural product ranged between 60.2 and 88.5% and those of PBA ranged between 37.8 and 89.5%. An actual-conditions surveillance analysis of six agricultural products imported from October to December 1994 indicated no phenothrin, but PBA was detected in all products.