Analytical Sciences

Direct Injection Method for Quantitation of Endogenous Leukotriene E₄ in Human Urine by Liquid Chromatography/Electrospray Ionization Tandem Mass Spectrometry with a Column-switching Technique

Naoya KISHI,  Nariyasu MANO, and Naoki ASAKAWA

Analytical Research Laboratories, Eisai Co. Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan

A new analytical method employing liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a column-switching system was developed for quantitative determination of leukotriene E₄ (LTE₄) in human urine. A column-switching 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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