尿中苯巯基尿酸的高效液相色谱-质谱测定方法

目的 研制我国职业接触苯工人尿中苯巯基尿酸(SPMA)的生物限值.方法 在苯作业车间选择空气中苯浓度在32.5 mg/m~3以下接苯工人55人,应用个体采样器采集空气样品,用气相色谱法检测作业者个体苯接触水平,同时采集当日工人班后尿,应用高压液相色谱/质谱法(HPLC/MS)测定尿中SPMA含量以评价苯接触者的内暴露水平,内外暴露水平的比较用相对内暴露指数(RIE)加以评定.结果 接苯工人工作环境空气苯浓度范围为0.71～32.17 mg/m~3,几何平均浓度为6.98 mg/m~3,中位数为7.50 mg/m~3,尿中SPMA与个体苯暴露量存在良好的线性关系Y(μg/g Cr)=-8.625+18.367 X(mg/m~3),r=0.8035(P<0.01);将我国职业苯接触限值时间加权平均容许浓度(PC-TWA=6 mg/m~3)代入回归方程,推算工作班后尿中SPMA含量为101.58μg/g Cr.计算的RIE指数显示,接触1 mg/m~3苯可平均代谢转化为尿中SPMA 18.23 μg/g Cr,并且随接苯水平的上升其代谢转化效率呈下降趋势.结论 参考国外SPMA生物限值标准,建议我国职业接触苯生物限值班后尿中SPMA为100μg/gCr(47μmol/mol Cr).

Establishment of biological limit value of urinary S-phenylmercapturic acid for occupational exposure to benzene

Objective To establish the biological exposure limit values of urinary S-phenylmercap-turic acid (SPMA) for assessing occupational exposure to benzene. Methods Study participants were selected from 55 workers of benzene exposures below 32.5 mg/m~3. The concentration of personal exposure to benzene was measured by gas chromatography and sampled with personal sampler. The urine samples were collected at the end of work shift and individual internal exposure level was evaluated by determination of SPMA in urine by HPLC/MS method. Comparison of external and internal exposure was assessed by the relative internal expo-sure(RIE) index. Results The benzene exposure level ranged from 0.71 to 32.17 mg/m~3 (geometric mean 6.98 mg/m~3, median 7.50 mg/m~3). The urinary SPMA at the end of the work shift were significantly correlated with benzene exposure, Y (μg/g Cr)=-8.625 + 18.367X (mg/m~3), r=0.8035, (P<0.01). According to the occupational exposure limit for benzene in China and calculation of regression equation, the expected value of urinary SPMA was 101.58 μg/g Cr. Mean level of biotransformation of per mg/m~3 benzene to urinary SPMA was 18.23 μg/g Cr and the metabolic efficiencies of benzene transformation to urinary SPMA decreased with benzene exposure in-creased. Conclusion Based on abroad documents and data, biological limit value for occupational exposure to benzene in China is recommended as follows: 100 μg/g Cr (47 μmol/mol Cr) for SPMA in the urine at the end of shift.