DETERMINATION OF MORPHINE AND ITS ANALOGS IN URINE BY ONLINE COUPLED REVERSED-PHASE LIQUID-CHROMATOGRAPHY GAS-CHROMATOGRAPHY WITH ONLINE DERIVATIZATION

An on-line coupled reversed-phase liquid chromatography-gas chromatogr aphy (RPLC-GC) method requiring minimal manual sample preparation was developed for the determination of morphine, codeine, heroin, dihydroc odeine and ethylmorphine in urine, A loop-type interface and concurren t eluent evaporation technique were used in the coupling, and the aque ous phase was changed to organic solvent by continuous liquid-liquid e xtraction before transfer to the CC. The two phases were separated wit h a sandwich-type phase-separator. The analytes were also derivatized on-line before CC separation. The LC was used for clean-up, and the GC for the final separation and detection of the analytes, Total analysi s time was less than 60 min, which is much shorter than with tradition al analysis methods. A marked increase in the recoveries in liquid-liq uid extraction (LLE) was obtained by heating the aqueous eluent and th e extraction coil. Linearity and repeatability of the method were good and the limits of quantification for the analytes were between 61 and 92 ng/ml.