采集来自不同人群的尿液样品10份，并在此基础上加入杜冷丁、美沙酮和可卡因等3种毒品的混合标准溶液配制多份加标尿样，其中毒品的含量分别为其检出限的1，2倍，测定下限的1，1.5，2，4，6，8倍。这些样品分别按以下方法处理：取尿液样品1.0 mL，加入100 g·L^-1氢氧化钠溶液15 μL，100 mg·L^-1内标溶液20 μL，加入环己烷1.0 mL进行超声提取，离心后取上清液200 μL，按仪器工作条件进行气相色谱-质谱法（GC-MS）测定。取空白尿液样品加入3种毒品的标准储备溶液，按上述方法绘制标准曲线，3种毒品的检出限（3S/N）依次为0.10，0.30，0.15 mg·L^-1。用Spss软件对所测得的6千多个数据进行统计处理，获得3种毒品保留时间的绝对偏差在±0.04 min（2.4 s）内，相对保留时间的相对偏差在±0.1%内。特征离子离子比率的绝对偏差和相对偏差的判定范围分别为±20%内和±50%内。上述结果可为尿液中3种常见毒品分析结果的判定提供实际数据和理论依据。

Ten samples of human urine were collected from various multitudes, and a series of the urine samples were prepared by addition of mixed standard solutions of the 3 drugs, meperidine, methadone and cocaine to the 10 urine samples with their concentrations of 1 and 2 fold of the detection limits and 1, 1.5, 2, 4, 6, and 8 fold of the lower limits of determination. Each of these samples was pretreated as follows:1.0 mL of the urine sample was taken and added with 15 μL of 100 g·L^-1 NaOH solution and 20 μL of the internal standard solution of 100 mg·L^-1. Then the solution was ultrasonically extracted with 1.0 mL of cyclohexane. After centrifugation, an aliquot of 200 μL of the supernatant was taken for GC-MS determination according to the working conditions of the instruments. Standard curves were prepared by addition of standard stock solution of the 3 drugs to blank urine samples and treated as described above. Detection limits (3S/N) of 0.10, 0.30, 0.15 mg·L^-1 were found for the 3 drugs respectively. About more than 6 000 data obtained in the analysis were treated statistically by using Spss software. The absolute deviations of retention time of the 3 drugs were found within ±0.04 min (2.4 s), and relative deviations of relative retention time of the 3 drugs were found to be within ±0.1%. Determination ranges of absolute deviations and relative deviations of ionic ratios of characteristic ions were ±20% and ±50%, respectively. The results obtained were the practical data and theoratical basis for judgement of analytical results of the 3 common drugs in urine.