分散液-液微萃取-气相色谱法测定尿中三氯乙酸

Determination of trichloroacetic acid in urine by dispersive liquid-liquid microextraction-gas chromatography

目的建立分散液-液微萃取-气相色谱法测定尿液中三氯乙酸的方法。方法在浓H2SO4催化下,尿中三氯乙酸与甲醇发生酯化反应,生成三氯乙酸甲酯,三氯乙酸甲酯通过分散液-液微萃取(DLLME),离心后吸取下层有机相注入气相色谱仪,经DB-FFAP毛细管色谱柱(30 m×0.32 mm,0.50μm)分离,采用氢火焰离子化检测器(FID)检测,以保留时间定性,峰面积定量。结果本法三氯乙酸在5.0 mg/L^200.0 mg/L浓度时呈线性,相关系数为0.999 1,以3倍噪音值估算方法检出限为2.6 mg/L。在10.0 mg/L^200.0 mg/L时添加低、中、高3个浓度水平,样品加标回收率为92.0%~96.5%;批内精密度为2.21%~3.22%(n=6),批间精密度为2.10%~4.29%(n=6);对20份尿样同时采用本法和国家标准方法 WS/T 64—1996测定,2种方法检测结果差异无统计学意义(P>0.05)。结论本法简单实用,有机试剂用量少,灵敏度高,可以满足尿样中三氯乙酸检测的要求。

Objective To establish a method for the determination of trichloroacetic acid in urine by dispersive liquid-liquid microextraction-gas chromatography（ DLLME）. Methods Trichloroacetic acid was esterified by methanol with H2SO4 as catalyst,and generated trichloroacetic acid methyl ester was extracted by DLLME. After extracted and centrifuged,trichloroacetic acid methyl ester was separated by DB-FFAP capillary column（ 30 m × 0. 32 mm,0. 50 μm） and detected by hydrogen flame ionization detector,with retention time for qualitative analysis and peak area for quantification. Results The detection limit of trichloroacetic acid in urine was 2. 6 mg/L（ S/N = 3）,and the standard curve was linear in the range of 5. 0 mg/L-200. 0 mg/L（ r = 0. 999 1）. The average recovery of trichloroacetic acid was within 92. 0%-96. 5% at three spiked levels in the range of10. 0 mg/L-200. 0 mg/L. The intra-day and inter-day precisions（ RSD） for the analysis were within 2. 21%-3. 22%（ n =6） and 2. 10%-4. 29%（ n = 6）,respectively. Twenty urine samples were detected by this method and the method of WS/T64—1996. There was no statistical significance on the difference between this two methods（ P〈0. 05）. Conclusion The method is simple,practical with less organic reagent consumption and highly sensitive,which could satisfy the request for the determination of trichloroacetic acid in urine.