A novel LC-ESI-MS-MS method for sensitive quantification of colchicine in human plasma: application to two case reports.

A novel method based upon liquid chromatography coupled to ion trap mass spectrometry (MS) detection with electrospray ionization interface has been developed for the identification and quantification of colchicine in plasma or whole blood. Colchicine was isolated from plasma using a liquid-liquid extraction with dichloromethane at pH 8.0 and embutramide as an internal standard, with satisfactory extraction recoveries. Solutes were separated on a 3-microm C18 Uptisphere (Interchim) column (150 x 2.0-mm i.d.) using acetonitrile/2 mM NH4COOH pH 3.8 buffer (50:50, v/v) as the mobile phase with a flow-rate of 200 microL/min. Data were collected either in full-scan MS mode at m/z 100-450 or in full-scan MS-MS mode, selecting the ion m/z 400.1 for colchicine and m/z 294.1 for embutramide. The most intense daughter ion of colchicine (m/z 358.1) and embutramide (m/z 207.9) were used for quantification. Retention times were 2.40 and 4.25 min for colchicine and embutramide, respectively. Calibration curves were linear in the 0.50-50 ng/mL range. The limits of detection and quantification were 0.05 ng/mL and 0.50 ng/mL, respectively. The intra- and interassay precisions were < 14%, and the intra- and interassay accuracies were in the 97-105.8% range at either 2 or 20 ng/mL. A fatal case of colchicine self-poisoning with a lethal blood concentration of 60 ng/mL and nonfatal case with a plasma sample collected very late (at least 36 h after the ingestion) are presented. The described method enables the unambiguous identification and quantification of colchicine with a very good sensitivity, using only 1 mL of sample.