James R. Fleeker

Metabolism of the butylcarbamoyl moiety of benomyl in rat

Abstract The metabolism of the butylcarbamoyl group was studied in the rat. [ 14 C]Benomyl-1-carbamoyl- n -[1- 3 H]butyl was fed orally, and 24 hr later 40% of the 14 C was found both in the urine and in the respired carbon dioxide. During the same period, 55–69% of the tritium was recovered in the urine. S -( n -Butylcarbamoyl)cysteine and S -( n -butylcarbamoyl)- N -acetylcysteine were found in the 24-hr urine and constituted 6–9% and 23–28%, respectively, of the tritium in that urine. A conjugate of butylamine, containing 42–47% of the tritium in the urine, was tentatively identified as the N -glucuronide derivative. The butylcarbamoyl group of benomyl is readity transferred to glutathione in vitro . N, N′ -dibutylurea, an in vitro decomposition product of benomyl, was not found in the urine of animals fed benomyl. When dibutylurea was fed to rats, 11–14% of the compound was recovered unchanged in the urine.

Improved quantitation of 2,4-dichlorophenol in plant tissues by high-performance liquid chromatography with amperometric detection

For the determination of 2,4-dichlorophenol (DCP) residues in plant tissues, the use of high-performance liquid chromatography with amperometric detection decreases the quantitation limits by a factor of five compared to those obtained with gas chromatography with Hall conductivity detection. It also avoids the clean-up and derivatization procedures required for electron-capture detection. After extraction of DCP from plant tissue by steam distillation and collection in toluene, an alumina clean-up column is used to remove electroactive interferences from the samples. The DCP is then extracted into aqueous alkaline solution, neutralized, and diluted with acetonitrile to ca. 50% (v/v). An alternative clean-up made use of an in-line, pre-column electrochemical procedure, in which case the alumina column was not used. The components were separated with a reverse-phase column and detected with a polychlorotrifluoroethylene/graphite composite electrode at an applied potential of +1.0 V vs. Ag/AgCl. The quantitation limit for DCP in the plant tissues was 100 pg per injection (0.05 mg Kg−1).

Detection of procymidone in wine and grapes by a magnetic particle‐based enzyme immunoassay

A competitive enzyme immunoassay has been developed to detect procymidone in wine at the parts per billion level (ppb) without sample dilution or extraction. This immunoassay utilizes magnetic particles as the solid phase which allows for the precise addition of antibody and rapid reaction kinetics. The sensitivity of the assay based on 90% B/Bo is 0.8 ppb in wine. The recovery of 30 wine samples spiked with four levels of procymidone averaged 104%. The specificity of the polyclonal antibody used allows for the quantitation of procymidone in the presence of other commonly applied fungicides including vinclozolin, iprodione, captan and carbendazim. Correlation of 27 wine samples by the immunoassay method and a GC/ ECD procedure yielded a regression (r) of 0.972. Recovery studies indicate that this immunoassay can also be used to detect procymidone on grapes. The average recovery of procymidone from grapes was 113%.