DEVELOPMENT OF HIGHLY SENSITIVE AND SPECIFIC HPLC ASSAY FOR PLASMA MORPHINE USING DIRECT-INJECTION TECHNIQUE AND POSTCOLUMN DERIVATIZATION

An extremely simple, rapid and reproducible analytical method was deve loped for the determination of morphine in human plasma using a high p erformance liquid chromatography utilizing a column-switching techniqu e and protein-coated precolumn. Morphine from plasma (500 mu L) was pr econcentrated on the protein-coated precolumn without sample pre-treat ment. This column acted at the same time as a clean up device. The dru g was transferred on-line to the analytical column followed by post-ch romatographic derivatization and fluorimetric detection. Post-column d erivatization was based on the oxidative dimerization of morphine to f luorescent pseudomorphine by potassium hexacyanoferrate (III). The ave rage morphine recoveries over a concentration range of 10 to 100 ng/mL ranged from 94.84 to 100.70%, and relative standard deviations ranged from 1.36 to 2.13%. (C) 1998 John Wiley & Sons, Ltd.