RESUMO
OBJECTIVE@#To develop a column-switching high-performance liquid chromatographic method for the determination of morphine and O6-monoacetylmorphine in urine.@*METHODS@#Urine samples (1.0 ml) were spiked with 1.0 ml borate buffer, after centrifugation, 1.0 ml of supernate were injected directly into an extraction column (YWG C18 33 mm x 5.0 mm, 10 microns). After a washing step with the extraction mobile phase, the retained morphine and O6-monoacetylmorphine were flushed into the analytical column (Lichrospher 100 CN 125 mm x 4.0 mm, 5 microns) with the mobile phase CH3OH-H2O (60:40). The analytical mobile phase is CH3OH-phosphate buffer (pH6.86) (22:78). The UV detector was set at lambda 286 nm.@*RESULTS@#The method shows excellent linearity from 50 to 1,600 ng/ml for morphine and from 100 to 1,600 ng/ml for O6-monoacetylmorphine. The linear correlation coefficients were > 0.999. The relative standard deviations were < 4%. The limits of detection were 40 ng/ml for both morphine and O6-monoacetylmorphine.@*CONCLUSION@#The method described is sensitive, rapid, reproducible, and simple.