COLUMN-SWITCHING SOLID-PHASE TRACE-ENRICHMENT HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR MEASUREMENT OF BUPRENORPHINE AND NORBUPRENORPHINE IN HUMAN PLASMA AND URINE BY ELECTROCHEMICAL DETECTION

We describe a new high-performance liquid chromatographic method using electrochemical detection for the determination of buprenorphine and norbuprenorphine in plasma and urine. The minimum concentration for de tection of buprenorphine and norbuprenorphine is 40 pg/ml. The intra-a ssay coefficient of variation (C.V.) in plasma and urine samples range s from 6 to 17% depending on the drug concentration. At a plasma conce ntration of 500 pg/ml the inter-assay C.V. is 8% for buprenorphine and 9% for norbuprenorphine. The analysis duration is 16 min. After solid -phase extraction and evaporation a valve-switching system with two Rh eodyne valves enables sample enrichment, optimal sample cleaning and r apid elution of long-retained substances.