Efficient method for the quantitation of urinary leukotriene E4 : Extraction using an Empore C18 disk cartridge

Abstract We describe here an efficient procedure for the precise quantitation of leukotriene E 4 (LTE 4 ) in a small volume of urine, which was achieved mainly by the use of an Empore extraction disk cartridge. After addition of [ 3 H]LTE 4 to 2 ml of urine, an Empore C 18 cartridge was used for initial extraction of the urine, which resulted in the extraction of LTE 4 in a small volume of solvent. The eluate could then be injected onto a high-performance liquid chromatography column without further concentration. After separation by high-performance liquid chromatography, LTE 4 was extracted from the effluent using an Empore C 18 cartridge. The concentration of LTE 4 was subsequently quantified by enzyme immunoassay. LTE 4 can be recovered from urine with sufficient efficiency (69.9±4.7%, mean±S.D., n = 101). The coefficient of variation of the assay procedure was less than 10%. When urine was spiked with different amounts of LTE 4 , the recovery of LTE 4 added to the urine specimen was less than 120%. The concentration of LTE 4 in urine from normal healthy subjects was 48.0±15.3 pg/mg creatinine ( n = 15).