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The enantiomerization and enantioselective metabolism of benalaxyl in mice after a single gavage administration were investigated in the present study. The pharmacokinetic result indicated that elimination of (−)-R-benalaxyl in plasma was slightly faster with the t 1/2 of 26.65 h and 28.88 h for (−)-R- and (+)-S-benalaxyl, respectively. Consistent with this, elimination in tissues and excretion were also enantioselective, with (+)-S-benalaxyl enriched in all tissues, urine and feces. And formation of the metabolites also exhibited an enantioselective manner. Both benalaxyl and most of its metabolites exhibited a potent excretion to feces and urine. In addition, significant enantiomerization of benalaxyl enantiomers was observed in plasma, with a larger extent from R to S than S to R. Thus, this difference in enantiomerization may be one of the reasons to explain the enantioselective enrichment of (+)-S-benalaxyl in mice observed in this study. Data from this study proves that besides metabolic enzymes, enantiomerization could be another important factor that contributes to the enantioselective metabolism of a chiral pesticide. Thus, research at enantiomeric level is necessary for efficient risk assessment of chiral pesticides. [ABSTRACT FROM AUTHOR]

Highlights: [•] Stereoselective transformation of triadimefon to triadimenol under field condition. [•] Enantioselective degradation of triadimefon in soil but not in wheat straw. [•] Prior formation of triadimenol diastereomer A in straw but diastereomer B in soil. [•] Predominant SR-(−)-triadimenol in straw but RR-(+)-triadimenol in soil. [Copyright &y& Elsevier]

• Fifty pesticides and eight metabolites in eggs were simultaneously detected. • Multi-functional filter based on QuEChERS were used to rapid sample preparation. • The efficiency was obviously improved with shorter cleanup time of < 1 min. • Acetamiprid, pyrimethanil and fipronil sulfone were detected in actual egg samples. A sensitive method for the simultaneous determination of 58 pesticides and relevant metabolites in eggs was developed using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) after clean-up with a multi-functional filter (MFF) based on quick, easy, cheap, effective, rugged, and safe method (QuEChERS). The egg sample was extracted with 5 ml water and 10 ml 1% acetic acid in acetonitrile and then salt out with sodium chloride. The extracted solution was filtered directly through an MFF containing 50 mg PSA, 50 mg C18, and 150 mg magnesium sulphate before UHPLC-MS/MS analysis. The clean-up and filter procedures were integrated using the MFF to substantially improve the work efficiency. Good linearity was shown for each analyte, and all the correlation coefficients exceeded 0.99. The recoveries in the eggs at the five spiked levels were 74.4%–115.2%, and the relative standard deviations (RSDs) were less than 15.3%. The limit of detection (LOD) and the limit of quantitation (LOQ) of 58 pesticides and 8 metabolites in eggs were 0.1–1.0 μg/kg and 0.2–5.0 μg/kg, respectively. The decision limit (CCα) and detection capacity (CCβ) were 3.4–111.1 μg/kg and 6.8–122.1 μg/kg, respectively. This method has also been successfully applied in the determination of actual eggs samples. This developed method is more effective and faster in the monitoring of pesticide residue in eggs compared to the traditional analytical method. [ABSTRACT FROM AUTHOR]

A fast method for the simultaneous determination of 14 antiviral drugs and relevant metabolites in chicken muscle by ultra-high liquid chromatography tandem mass spectrometry (UPLC–MS/MS) was developed. The analytes included anti-influenza drugs (amantadine, rimantadine, oseltamivir, oseltamivir carboxylate, memantine, arbidol, and moroxydine), anti-herpes drugs (acyclovir, ganciclovir, famciclovir, penciclovir, ribavirin and its main metabolite TCONH 2 ), and an immunomodulator (imiquimod). The samples were pretreated using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method. The determination of the target compounds was conducted in less than 11.0 min, and specificity was ensured by the use of multiple reaction monitoring (MRM) acquisition mode. Good linearities ( R 2 > 0.9928) were obtained in the range of 0.1–100 μg/L, and the recovery rates were 56.2–113.4% with RSDs of 1.7–10.3% for intra-day precision and 2.4–8.8% for inter-day precision. The LODs and LOQs of all analytes were in the ranges of 0.02–1.0 and 0.05–2.5 μg/kg, respectively. An analysis of real samples suggested that this method is simple, sensitive, reliable and practical for the detection of antiviral drugs in animal tissue. [ABSTRACT FROM AUTHOR]