Determination of heroin and its main metabolites in small sample volumes of whole blood and brain tissue by reversed-phase liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS) method has been developed for the quantitative analysis of heroin and its major metabolites 6-acetylmorphine, morphine, morphine-3-glucuronide and morphine-6-glucuronide in blood and brain tissue, using 0.1-mL samples. We evaluated this method for analysis of heroin and its metabolites in samples from heroin treated mice. Ice-cold acidic buffer containing sodium fluoride was immediately added to blood and brain homogenate samples. Sample preparation was achieved by protein precipitation on ice-bath, using a mixture of ice-cold acetonitrile and methanol. The supernatant was evaporated to dryness, reconstituted with mobile phase, and injected into the chromatographic system. Separation was performed on a Xterra C18 column with gradient elution. The MS analysis was performed in positive ion mode, and multiple reaction monitoring (MRM) was used for drug quantification. The limits of quantification for the different opiates varied from 0.0007 to 0.02 mg/L in blood and from 0.002 to 0.06 microg/g in brain tissue. Day-to-day relative standard deviation ranged from 3.1 to 14.5%, and within-day variation ranged from 2.1 to 11.4%. The recoveries were between 80 and 111%. The stability of heroin was tested, and the study showed that heroin is more stable in brain tissue than in blood.