Gas Chromatography/Mass Spectrometry Identification and Quantification of Isazophos in a Famphur Pour-On and in Bovine Tissues after a Toxic Exposure

Abstract

A sample identified as "Warbex pour-on," expected to contain 13.2% famphur, and bovine tissue samples from 2 heifers that died after exhibiting signs of organophosphate intoxication were analyzed by gas chromatography/mass spectrometry (GC/MS). A product formulation problem was suspected because brain cholinesterase activities were depressed in both animals. Electron impact (EI) GC/MS of the pour-on revealed 9.7% famphur and an unidentified peak with approximately 76% of the peak area of the famphur. The unidentified peak showed a molecular ion at m/z 313, with a single Cl isotope cluster. Methane chemical ionization (MeCI) MS confirmed the molecular weight at 313 (1 Cl). A search on the molecular formula C9H17N3O3PSCl yielded a single match, isazophos. EI and MeCI GC/MS of reference isazophos confirmed the identity of the suspect peak. The concentration of isazophos in the pour-on was determined to be 6.0%. Famphur and isazophos were identified by their EI spectra and GC retention times in extracts of liver and brain from the 2 deceased animals. A GC/MS procedure utilizing selected ion monitoring (SIM) was developed for quantification of isazophos in liver, kidney, muscle, and fat of additional affected animals sacrificed at various times after exposure. Isazophos remained in animal tissues for as long as 94 days after topical exposure. Isazophos was present in fetal liver 70 days after exposure of the dam. High levels (6-3,500 ppm) of isazophos and famphur remained on the skin at 39 days postexposure.

Avian Mortality Events in the United States Caused by Anticholinesterase Pesticides: A Retrospective Summary of National Wildlife Health Center Records from 1980 to 2000

“…Another 9% of the analyses on gastrointestinal contents were done at the National Fish and Wildlife Forensics Laboratory (NFWFL), Ashland, OR, using GC/MS for OPs and highperformance liquid chromatography and GC/MS for CBs (NFWFL standard operating procedures TOX-002 and TOX-003, respectively). The remaining 10% of chemical analyses were done at the Animal Health Diagnostic Laboratory (ADHL) at Michigan State University, Lansing (Braselton et al 2000), Wisconsin Central Animal Health Laboratory, Madison (US FDA 1977), Laboratory Services Division of the Oregon Department of Agriculture, Salem (Luke et al 1981), Virginia Department of General Services, Division of Consolidated Laboratory Services, Richmond (Stahr 1980), and Pesticide Residue Laboratory, Biochemistry Department of Virginia Polytechnic Institute and State University, Blacksburg (Bertuzzi et al 1967;Shuttleworth 1973).…”

Determination of methomyl in the stomach contents of baited wildlife by gas chromatography–mass spectrometry

“…1 However, acute poisonings do occur and may be accompanied by symptoms including drowsiness, sialorrhea, diarrhea, tremors, and death due to paralysis of respiratory muscles. 3 Methomyl is considered a highly toxic compound with an oral median lethal dose (LD 50 ) of 12-48 mg/kg in rats. 1 Carbamates are the most common class of pesticides involved in animal poisonings in Europe and the United States.…”

“…3 Specifically, 20 g of sample, 2 ml of a 20 µg/ml diphenylamine internal standard, and 300 ml of acetonitrile were combined, blended to homogeneity, and then filtered. The filtrate was transferred to a separatory funnel containing 10 ml of saturated sodium chloride solution, 600 ml of ultrapure water, and 100 ml of methylene chloride; extraction was performed by shaking and allowing the phases to separate.…”

Thin Layer Chromatography Convulsant Screen Extended by Gas Chromatography-Mass Spectrometry

“…3,4 Several of the above (insecticides, metaldehyde, and drugs of abuse) can be identified in a single gas chromatography-mass spectrometry (GC-MS) screen, 1 but most have to be determined by individual tests. To identify additional suspect toxicants in strychnine negative samples, an extraction procedure for neutral compounds as well as alkaloids was developed.…”

“…Qualitative GC-MS was carried out on the mass selective detector (MSD) as described previously. 1 The equipment used for 70 eV electron-impact (EI) mass spectrometry consisted of an autosampler interfaced to a GC and MSD. g The GC column was a 30 m ϫ 0.25 mm ID ϫ 0.25 m (film) DB-5MS.…”