title: An LC/MS/MS method for improved quantitation of the bound residues in the tissues of animals orally dosed with [(14)C]Benomyl.
abstract: Livers of goats orally dosed with [phenyl(U)-(14)C]benomyl contained radioactive residues which were not extractable using conventional, solvent-based extraction methods. We report a new residue method capable of enhanced extraction of benomyl-derived residues with selective and sensitive quantitation capability for methyl 4-hydroxybenzimidazol-2-ylcarbamate (4-HBC), methyl 5-hydroxybenzimidazol-2-ylcarbamate (5-HBC), and methyl benzimidazol-2-ylcarbamate (MBC). This method involves rigorous Raney-nickel reduction of hypothesized thioether bonds between benomyl residues and polar cellular components. Following acidic dehydration (desulfurization), the polar benomyl-derived residues are extracted into ethyl acetate and analyzed by LC/MS/MS. We have shown this method to be superior to alternative extraction approaches. When applied to goat liver tissue containing [phenyl(U)-(14)C]benomyl-bound residues, the extraction efficiency of total radioactive residues was approximately 30%, and the major benomyl-derived residue was 5-HBC (91-95% of extractable residue) with minor levels of carbendazim (MBC) (5-9%). HPLC/LSC data were consistent with the LC/MS/MS data. The overall method satisfies U.S. regulatory requirements in extraction efficiency, selectivity in detection, and limits of quantitation for benomyl-bound residues.
authors.affiliation: Nutrition and Health, Stine-Haskell Research Center, The DuPont Company, 1090 Elkton Road, P.O. Box 30, Newark, Delaware 19711, USA. Moghaddam@USA.dupont.com
authors.forename: M F
authors.initials: MF
authors.lastname: Moghaddam
authors.forename: R K
authors.initials: RK
authors.lastname: Trubey
authors.forename: J J
authors.initials: JJ
authors.lastname: Anderson
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001542:Benomyl / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001562:Benzimidazoles / Q000032:analysis; D002138:Calibration; D002219:Carbamates; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D004350:Drug Residues / Q000032:analysis*; D005260:Female; D005659:Fungicides, Industrial / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006041:Goats; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D011865:Radioisotope Dilution Technique
chemical_list: D001562:Benzimidazoles; D002219:Carbamates; D002250:Carbon Radioisotopes; D005659:Fungicides, Industrial; C006698:carbendazim; D001542:Benomyl