To detect sub-ppb levels of the antibiotic chloramphenicol in honey matrix, a convenient method of extraction and measurement using liquid chromatography with detection by tandem mass spectrometry (LC/MS/MS) was developed. Honey samples fortified with chloramphenicol and isotopically labeled chloramphenicol were extracted using diatomaceous-based supported liquid-liquid extraction cartridges to generate a standard calibration curve. Four MS/MS transitions were used for quantification and four other transitions for confirmation of chloramphenicol. The limit of detection for chloramphenicol was 0.05 ng/g and the lower limit of quantification was 0.1 ng/g. Several commercial honey samples were analyzed for chloramphenicol content using this method.

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A strategy is developed for the identification of isocephalomannine in the presence of alkali metal ion adducts and other cephalomannine isomers in a paclitaxel active pharmaceutical ingredient. Intact molecular ion analyses and a sub-structural study have been performed for the differentiation of isocephalomannine (2-debenzoylpaclitaxel-2-pentenoate) from cephalomannine and 7-epi-cephalomannine. A comparative study of the cephalomannine isomers was carried out using molecular ions (MS) and fragmentation patterns (MS/MS) for sub-structural analysis. An attempt has been made to identify isocephalomannine in Cremophor(R) EL formulations.