A multiresidue screen for the analysis of toxicants in bovine rumen contents.

Analysis of rumen contents is helpful in solving poisoning cases when ingestion of a toxic substance by cattle or other ruminant animals is suspected. The most common technique employs extraction of the sample with organic solvent followed by clean-up method(s) before analysis with gas chromatography-mass spectrometry equipped with a library of mass spectra to help identify unknowns. A rapid method using magnesium sulfate, primary secondary amine, and C18 sorbents following principles of QuEChERS to clean up rumen contents samples is reported herein. The method was validated to analyze fortified bovine rumen contents to detect commonly found organophosphorus pesticides, carbamates, and several other compounds such as atropine, 4-aminopyridine, caffeine, scopolamine, 3-chloro-4-methylaniline, strychnine, metaldehyde, and metronidazole. For each compound, the ratio of 2 ions from the mass spectrum was monitored in fortified rumen contents. The ion ratio of fortified sample was compared with the ion ratio of standard sample spectrum and was found to be within 20%, with the exception of aldicarb and 4-aminopyridine with ion ratio of 26% and 29%, respectively. Usefulness of the method was demonstrated by not only analyzing bovine rumen contents but also canine and avian gastrointestinal contents submitted for organic chemical screening.

Determination of acepromazine, ketamine, medetomidine, and xylazine in serum: multi-residue screening by liquid chromatography-mass spectrometry.

A large variety of drugs are administered to large and small animals by veterinary clinicians for sedation, anesthesia, muscle relaxation, and analgesia. The present paper reports a simple and rapid multi-residue detection and quantitation method for four chemically different drugs: medetomidine, xylazine, ketamine, and acepromazine. Chromatographic separation was carried out on a liquid chromatography-mass spectrometry instrument with a C18-reversed-phase column. Fragmentation patterns were determined with atmospheric pressure chemical ionization mass spectrometry set to operate in a positive selective ion monitoring mode. The method was determined to be linear over the range of concentrations tested (2.0-100.0 ng/mL). Accuracy, precision, and specificity were evaluated and the method was determined to be applicable to detection of medetomidine, xylazine, ketamine, and acepromazine in serum samples of multiple animal species (canine, equine, and bovine). Matrix limits of quantitation were determined to be 5.0 ng/mL for all four analytes, and recoveries ranged between 82.0 and 118%, with a 3.0-18.3% relative standard deviation.

Multi-residue determination of anti-inflammatory analgesics in sera by liquid chromatography--mass spectrometry.

Non-steroidal anti-inflammatories (NSAIDs) are analgesic, antipyretic, and, as their name implies, anti-inflammatory drugs, which are widely used for the treatment of a variety of human and veterinary disease conditions in which control of pain and inflammation is desired. Acetaminophen (ACE) is a common over-the-counter analgesic. Detection of a variety of widely used NSAIDs and ACE in fluid and tissue samples is an important diagnostic tool. A sensitive and selective analytical method has been developed for simultaneous screening of 12 NSAIDs and ACE by liquid chromatography-mass spectrometry with an atmospheric pressure chemical ionization interface set to operate in the negative ion mode of MS. Following sample preparation, all analytes were separated on a C18-reversed-phase column with a gradient elution of acetonitrile and acetic acid. Full-scan mass spectral fragmentation profiles were established for each analyte and individual extracted ion chromatograms were used for quantitation. Linearity of detection was observed over the 0.05-25.0 microg/mL range of standard concentrations. The instrument limits of detection (LOD), based on an individual analyte quantitation ions, fell between 0.05 and 1.0 microg/mL for all compounds. The matrix LODs were determined to be 0.05 microg/mL for phenylbutazone (m/z 307); 0.1 microg/mL for indomethacin (m/z 312), flunixin (m/z 295), and piroxicam (m/z 330); 0.5 microg/mL for ACE (m/z 150), diclofenac (m/z 250), ketoprofen (m/z 209), and mefenamic acid (m/z 240); 1.0 microg/mL for oxyphenbutazone (m/z 323); 5.0 microg/mL for ibuprofen (m/z 205), salicylic acid (m/z 137), and tolmetin (m/z 212); and 10 microg/mL for naproxen (m/z 185).