Paci E, Pigini D, Cialdella A M, Faranda P, Tranfo G
Italian Institute for Occupational Safety and Prevention (ISPESL), Occupational Hygiene Department, Monte Porzio Catone, Italy.
Biomarkers. 2007 Mar-Apr;12(2):111-22. doi: 10.1080/13547500601007943.
Urinary S-phenylmercapturic acid (SPMA) is a biomarker suggested by the American Conference of Governmental Industrial Hygienists (ACGIH) for assessing occupational exposure to benzene. A possible cause of the miscorrelation between environmental monitoring and biological monitoring for benzene exposure, which many authors complain about, is the existence of a urinary metabolite that turns into SPMA by acid hydrolysis. Forty urine samples were tested to determine which concentration value would correspond to the ACGIH Biological Exposure Index (BEI) of 25 microg g(-1) creatinine if exposure assessment was based on the determination of SPMA after quantitative hydrolysis of its precursor. An aliquot of each sample was hydrolysed with 9 M H2SO4, a second one was brought to pH 2 and a third one was used as it was (free SPMA). SPMA was determined by high-performance liquid chromatography/tandem mass spectrometric technique (HPLC/MS/MS) using an internal standard. The analytical method was validated in the range 0.5-50 microg 1(-1). The average SPMA in pH 2 samples is 45-60% of the total, while free SPMA varies from 1% to 66%. The hydrolysis of pre-SPMA reduces the likelihood of variability in the results by reducing pH differences in urine samples and increasing the amount of measured SPMA. The BEI limit value would be about 50 microg g(-1) creatinine.
尿中S-苯巯基尿酸（SPMA）是美国政府工业卫生学家会议（ACGIH）建议用于评估职业性苯暴露的生物标志物。许多作者抱怨的苯暴露环境监测与生物监测之间误相关的一个可能原因是存在一种经酸水解后转化为SPMA的尿代谢物。对40份尿液样本进行检测，以确定如果基于其前体定量水解后SPMA的测定进行暴露评估，哪个浓度值将对应于ACGIH生物暴露指数（BEI）25μg g⁻¹肌酐。每个样本的一份等分试样用9M H₂SO₄水解，另一份调至pH 2，第三份原样使用（游离SPMA）。采用内标法通过高效液相色谱/串联质谱技术（HPLC/MS/MS）测定SPMA。该分析方法在0.5 - 50μg 1⁻¹范围内得到验证。pH 2样本中SPMA的平均值占总量的45% - 60%，而游离SPMA在1%至66%之间变化。前体SPMA的水解通过减少尿液样本中的pH差异并增加测得的SPMA量，降低了结果变异性的可能性。BEI限值约为50μg g⁻¹肌酐。
