HPLC determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in human serum of oncological patients after administration of morphine drugs.

A simultaneous determination of morphine (M) and its two metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), by HPLC in the serum of oncological patients is described. The compounds are extracted from the serum by means of Chromabond C18--EC solid-phase-extraction cartridges, separated on a Symmetry C18 analytical column (150 x 4.9 mm, 5 microm) and detected by a UV detector at 210 nm. The mobile phase consisted of 8% acetonitrile in water, 30 mmol/l phosphate buffer (pH 3) and 1 mmol/l octane sulfonic acid as the ion pairing agent; its flow-rate was 0.8 ml/min. Under these conditions, the detection limits were 10 ng/ml, 60 ng/ml and 90 ng/ml for M, M3G, and M6G, respectively. This paper concerns blood serum concentration levels of M, M3G and M6G in oncological patients, their ratios and their role in pain resistance.