Direct injection method for quantitation of endogenous leukotriene E-4 in human urine by liquid chromatography/electrospray ionization tandem mass spectrometry with a column-switching technique

A new analytical method employing liquid chromatography/tandem mass spectro metry (LC/MS/MS) with a column-switching system was developed for quantitat ive determination of leukotriene E-4 (LTE4) in human urine. A column-switch ing system using a trapping column, which concentrates the analyte and remo ves salts and other water-soluble contaminants, allowed direct injection of human urine. Because simultaneously eluted endogenous contaminants suppres sed the ionization efficiency of LTE4, good liquid chromatographic separati on was very important for establishing this method, notwithstanding the hig h selectivity of MS/MS. The calibration curve was linear over the range fro m 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 i n human urine in studies on leukotriene metabolism and the efficacy of anti leukotriene drugs.