建立了气泡微萃取结合气相色谱/质谱技术(GC-MS)测定尿中咖啡因的方法.对影响萃取效率的实验条件进行了优化,确定了最佳萃取条件:三氯甲烷作为萃取溶剂,萃取溶剂暴露体积1 μL,气泡体积1.6 μL,搅拌速度300 r/min,萃取时间5 min,盐度15%(m/V),气泡与磁子间距离1 cm.在优化条件下,所建立方法在咖啡因浓度0.005~10 mg/L范围内有较好的线性关系,相关系数可达0.986,检出限为0.003 mg/L.在人尿液中添加不同浓度的咖啡因(0.050、0.500和5.000 mg/L),回收率为89.2%~107.5%,相对标准偏差小于8%(n=6).%A method for the determination of caffeine in urea was developed based on bubble-in-drop single drop microextraction (BID-SDME) followed by gas chromatography/mass spectrometry (GC-MS).Under the optimum conditions including chloroform as extraction solvent, an exposure volume of 1 μL, a bubble volume of 1.6 μL, stirring for 5 min at 300 r/min, 15% (m/V) NaCl, and a distance of 1 cm between bubble and stirring bar, the detection limit of this method was as low as 0.003 mg/L and the linear range was from 0.005 mg/L to 10 mg/L with correlation coefficient of 0.982.The recoveries of caffeine were from 89.2% to 107.5% at different spiked levels in human urine and the relative standard deviation (RSD, n=6) was less than 8%.
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