提出了固相萃取-液相色谱-串联质谱法测定尿液中四氢大麻酚(THC)和Δ⁹-四氢大麻酸(THC-COOH)含量的方法。取尿液样品1 mL,加入1 mol·L^-1 NaOH溶液1 mL,于60 ℃加热15 min后过活化好的MAX混合阴离子固相萃取柱。用1 mL 2%(体积分数)氨水溶液固定目标物,用1 mL 80%(体积分数)甲醇溶液进行淋洗,最后用1 mL含5%(体积分数)甲酸的甲醇溶液进行洗脱,收集洗脱液,按照仪器工作条件进行测定。以Agilent Poroshell HPH-C₁₈色谱柱(50 mm×4.6 mm,4 μm)为固定相,以不同体积比的5 mmol·L^-1乙酸铵溶液-甲醇混合液为流动相进行梯度洗脱;分离后的THC和THC-COOH经电喷雾离子源负离子模式扫描,多反应监测模式检测。结果表明:THC和THC-COOH的质量浓度在一定范围内与对应的峰面积呈线性关系,检出限(3S/N)分别为0.003,0.05 μg·L^-1;按照标准加入法对空白样品进行加标回收试验,回收率为81.2%~99.0%,日内精密度(n=5)为1.1%~6.0%,日间精密度(n=5)为2.2%~6.4%;方法用于一份疑似吸食大麻人员的尿液样品分析,检出THC和THC-COOH,检出量分别为5.8 μg·L^-1和56.6 μg·L^-1。

A method for the determination of tetrahydrocannabinol (THC) and Δ⁹-tetrahydrocannabinic acid (THC-COOH) in urine by liquid chromatography-tandem mass spectrometry with solid phase extraction was proposed. The urine sample (1 mL) was taken, and 1 mL of 1 mol·L^-1 NaOH solution was added. The mixed solution was heated at 60 ℃ for 15 min, and then passed through activated MAX mixed anionic solid phase extraction column. Using 1 mL of 2% (volume fraction) ammonia solution to fix the targets, with 1 mL of 80% (volume fraction) methanol solution for rinsing, and 1 mL of methanol solution containing 5% (volume fraction) formic acid for elution, the collected eluent was determined according to the working conditions of the instrument. Gradient elution was performed using Agilent Poroshell HPH-C₁₈ column (50 mm×4.6 mm, 4 μm) as the stationary phase, and the mixed solutions composed of 5 mmol·L^-1 ammonium solution and methanol with different volume ratios as the mobile phase. The separated THC and THC-COOH were scanned by electrospray ion source with negative ion mode, and detected by multi-reaction monitoring mode. It was shown that linear relationships between the mass concentrations and corresponding peak areas of THC and THC-COOH were kept in definite ranges, with detection limits (3S/N) of 0.003 μg·L^-1 and 0.05 μg·L^-1, respectively. Test for recovery was made on the blank sample by standard addition method, giving results in the range of 81.2%-99.0%, with precisions of intra-day (n=5) and inter-day (n=5) were in the ranges of 1.1%-6.0% and 2.2%-6.4%, respectively. The method was used to analyze one urine sample of a suspected cannabis user, in which THC and THC-COOH were detected, with detection amounts of 5.8 μg·L^-1 and 56.6 μg·L^-1, respectively.