[Simultaneous analyses of cocaine and its metabolite benzoylecgonine in urine by LC-MS/MS].

OBJECTIVE: To establish a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of cocaine (COC) and its metabolite benzoylecgonine(BZE) in urine samples. METHODS: A single dose of COC (10 mg/kg) was injected intraperitoneally into guinea pigs and urine samples were collected for 7 days. The urine samples were extracted by auto solid phase extraction (SPE), separated by the Allure PFP propyl column with a mobile phase consisting of methanol and 20 mmol/L ammonium acetate buffer [0.1% formic acid (80:20, V/V)], and then analyzed by LC-MS/MS. Multiple reaction monitoring (MRM) mode was used to analyze COC (m/z 304.2-->182.3, m/z 304.2-->150.1) and BZE (m/z 290.2-->168.3, m/z 290.2-->105.0). RESULTS: COC and BZE showed a fairly good linearity over the range of 2.0-100 ng/mL (r=0.9995). The detection limit was 0.5 ng/mL. The recovery rate was greater than 90% and the deviation of intra- and inter-day precision was less than 6%. BZE was the major target detected in urine samples, and its detection window was longer than COC. CONCLUSION: This newly developed method shows high sensitivity and selectivity, and is suitable for the simultaneous analysis of cocaine and benzoylecgonine in urine samples.