Benzene, toluene, ethylbenzene, and xylene (BTEX) are a group of volatile organic compounds that are ubiquitous in the environment due to numerous anthropogenic sources. Exposure to BTEX poses a health hazard by increasing the risk for damage to multiple organs, neurocognitive impairment and birth defects. Urinary BTEX metabolites are useful biomarkers for the evaluation of BTEX exposure, because of the ease of sampling and their longer physiological half-lives compared with parent compounds. A method that utilizes LC-MS/MS was developed and validated for simultaneously monitoring of 10 urinary BTEX metabolites. During the sample preparation an aliquot of urine was diluted with an equal volume of 1% formic acid; internal standard solution was added, and then the sample was centrifuged and analyzed.The analytes were separated on the Kinetex-F5 column by applying a linear gradient, consisting of 0.1% formic acid and methanol. The method was validated according to the FDA Bioanalytical Method Validation Guidance for Industry. The mean method's accuracies of the spiked matrix were 81-122%; the inter-day precision ranged from 4 to 20%; the limits of quantitation were 0.5-2 μg/L. The method was used for the evaluation of baseline levels of urinary BTEX metabolites in 87 firefighters.

A high-throughput LC-MS/MS method for simultaneous identification and quantitation of eight non-steroidal anti-inflammatory drugs (NSAIDs) and chloramphenicol (CAP) in bovine and ovine milk was developed. The method is capable of detecting and quantitating: Carprofen (CPF), tolfenamic acid (TLF), 5-hydroxy flunixin (FLU-OH), diclofenac (DCL), 4-methylaminoantipyrin (4MAA), meloxicam (MLX), ibuprofen (IBU), phenylbutazone (PBZ) and chloramphenicol (CAP) at their maximum residue limits (MRLs) or target analytical levels. Addition of ascorbic acid into the milk samples before the extraction step was found to be crucial for repeatability and intensity of PBZ and 4MAA. The method consists of the single extraction step with acetonitrile and a commercially available salt mixture, followed by evaporation of the supernatant and reconstitution. Complementary LC-MS/MS and LC-MS/MS/MS methods were developed for confirmation of ibuprofen and diclofenac respectively. The method was validated according to EU Commission Decision 2002/657/EC requirements. The method accuracy was in the range of 89-108% and coefficients of variation of the interday precision assessment varied between 3% and 16%. This method has been implemented at the Israel National Residue Control Laboratory for routine monitoring of NSAIDs and CAP residues in bovine and ovine milk.

A high-throughput LC-MS/MS method for simultaneous identification and quantitation of eight non-steroidal anti-inflammatory drugs (NSAIDs) and chloramphenicol (CAP) in bovine and ovine milk was developed. The method is capable of detecting and quantitating: Carprofen (CPF), tolfenamic acid (TLF), 5-hydroxy flunixin (FLU-OH), diclofenac (DCL), 4-methylaminoantipyrin (4MAA), meloxicam (MLX), ibuprofen (IBU), phenylbutazone (PBZ) and chloramphenicol (CAP) at their maximum residue limits (MRLs) or target analytical levels. Addition of ascorbic acid into the milk samples before the extraction step was found to be crucial for repeatability and intensity of PBZ and 4MAA. The method consists of the single extraction step with acetonitrile and a commercially available salt mixture, followed by evaporation of the supernatant and reconstitution. Complementary LC-MS/MS and LC-MS/MS/MS methods were developed for confirmation of ibuprofen and diclofenac respectively. The method was validated according to EU Commission Decision 2002/657/EC requirements. The method accuracy was in the range of 89-108% and coefficients of variation of the interday precision assessment varied between 3% and 16%. This method has been implemented at the Israel National Residue Control Laboratory for routine monitoring of NSAIDs and CAP residues in bovine and ovine milk.