A new analytical method employing liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a columnswitching system was developed for quantitative determination of leukotriene E4 (LTE4) in human urine. A columnswitching system using a trapping column, which concentrates the analyte and removes salts and other water-soluble contaminants, allowed direct injection of human urine. Because simultaneously eluted endogenous contaminants suppressed the ionization efficiency of LTE4, good liquid chromatographic separation was very important for establishing this method, notwithstanding the high selectivity of MS/MS. The calibration curve was linear over the range from 10 to 3000 pg/mL, and the method showed good accuracy and precision. This method should therefore be very useful for determination of LTE4 amounts in human urine in studies on leukotriene metabolism and the efficacy of antileukotriene drugs.

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A dried linseed film was analyzed by two-stage pyrolysis-gas chromatography/mass spectrometry (Py-GC/ MS) to investigate its structure and pyrolysis mechanisms. Heating furnace temperatures appropriate to the pyrolysis were determined to be 300ῌ and 600ῌ by thermogravimetry/di#erential thermal analysis῍mass spectrometry (TG/DTA-MS). The dried linseed film was then pyrolyzed at 300ῌ and 600ῌ. From the pyrolysis at 300ῌ, saturated and monoenyl fatty acids were detected, and the relative peak intensities of hexadecanoic acid and of octadecanoic acid were highest. These fatty acids are the pyrolysis products of the terminal groups. The dried linseed film is terminated with saturated and monoenyl fatty acid esters, especially with hexadecanoic acid ester and octadecanoic acid ester. From the pyrolysis at 600ῌ, alkenes, alkanes and fatty acids were detected. Some alkenes and alkanes have carbon chains longer than the side chains of the glycerides. The alkenes and alkanes are the pyrolysis products of the glyceride polymers generated by the autoxidative C῍C cross-linking. The formation of fatty acids is also attributed to the cross-links of the glyceride polymers. These results reveal that autoxidative cross-linking proceeds through the polymerization of linseed oil.