Yoshichika Hirahara

Analysis of Phenothrin and Its Metabolite 3-Phenoxybenzoic Acid (PBA) in Agricultural Products by GC and Ion-Trap GC/MS

A sensitive method for analysis of phenothrin 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 (Cl) was investigated. After phenothrin in vegetables, fruits, potatoes, starches, and tea had been extracted with acetone, or in cereals and beans had been extracted with acetonitrile followed by Florisi! 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.

Studies on Systematic Determination of Organophosphorus, Carbamate, Organochlorine and Pyrethroid Pesticides in Polished Rice by Gas Chromatography

A method for systematic determination of organophosphorus, carbamate, organochlorine and pyrethroid pesticides in polished rice by GC was developed. The pesticides were extracted from the sample with acetone-water (7:3) mixture, and re-extracted into ethyl acetate. Organophosphorus pesticides in the extract were directly determined without purification. On the other hand, half of the extract was purified over a Florisil column and used for determination of organochlorine and pyrethroid pesticides. The other half of the extract was purified on a silica gel column and used for determination of carbamate pesticides. No pesticide was found in 56 samples of polished rice from Thailand. The detection limit of the proposed method was 0.001ppm for organophosphorus and organochlorine pesticides and 0.01ppm for carbamate and pyrethroid pesticides.

Simultaneous Determination of Residual Synthetic Antibacterials in Edible Viscera by High Performance Liquid Chromatography.

The simultaneous determination of residual 13 synthetic antibacterials in edible viscera by HPLC was studied and the clean up method was developed by Sep-Pak Alumina N and also tC18 cartridges. This method was applicable to sulfamerazine, sulfadimidine, sulfamonomethoxine, sulfadimethoxine, sulfaquinoxaline, ormethoprim, trimethoprim, pyrimethamine difulazon, clopidol, morantel, carbadox and nicarbazin in the bovine liver and swine kidney. The recoveries of the addition of 0.4μg/g of these antibacterials to the bovine liver and to the swine kidney were in the range of 54.0 to 74.9%, and their detection limits were in the range of 30 to 50 ppb.