EFFICIENT METHOD FOR THE QUANTITATION OF URINARY LEUKOTRIENE E-4 - EXTRACTION USING AN EMPORE C-18 DISK CARTRIDGE

We describe here an efficient procedure for the precise quantitation o f leukotriene E-4 (LTE4) in a small volume of urine, which was achieve d mainly by the use of an Empore extraction disk cartridge. After addi tion of [H-3]LTE4 to 2 mi of urine, an Empore C-18 cartridge was used for initial extraction of the urine, which resulted in the extraction of LTE4 in a small volume of solvent. The eluate could then be injecte d onto a high-performance liquid chromatography column without further concentration. After separation by high-performance liquid chromatogr aphy, LTE4 was extracted from the effluent using an Empore C-18 cartri dge. The concentration of LTE4 was subsequently quantified by enzyme i mmunoassay. LTE4 can be recovered from urine with sufficient efficienc y (69.9+/-4.7%, mean+/-S.D., n=101). The coefficient of variation of t he assay procedure was less than 10%. When urine was spiked with diffe rent amounts of LTE4, the recovery of LTE4 added to the urine specimen was less than 120%. The concentration of LTE4 in urine from normal he althy subjects was 48.0+/-15.3 pg/mg creatinine (n=15).