Negri S, Alessio A, Maestri L, Sgroi M, Ghittori S, Imbriani M
Laboratorio Monitoraggio Esposizione Inquinanti Aeriformi, Fondazione S. Maugeri, IRCCS, Istituto di Pavia.
G Ital Med Lav Ergon. 2001 Oct-Dec;23(4):461-6.
N,N-dimethylformamide (DMF) is a solvent widely used to prepare synthetic fibers. Biomonitoring of DMF is usually performed by measuring urinary N-methylformamide, which allows us to estimate exposure during the working day. An alternative biomarker is the mercapturic acid N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) whose excretion accounts for about 13% of the absorbed DMF dose. Owing to its slow excretion (mean half-life = 23 hours) the urinary levels of AMCC at the end of a workweek reflect the cumulative dose of DMF during the whole week. Methods given in literature for measuring AMCC need the derivatization of the molecule before analysis. The paper describes a method for the determination of urinary AMCC by high-performance liquid chromatography (HPLC) with direct UV detection. Samples were purified by solid phase extraction with C18 and ENV+ cartridges, then 10 microliters were directly injected onto an Aminex HPX-87H Ion Exclusion column maintained at a temperature of 37 degrees C. Analyses were performed by isocratic run with 1 mM sulphuric acid delivered at 0.85 mL/min. The detector was set at 196 nm. Under these conditions, AMCC eluted at 11.1 min., and the detection and quantification limits were 1.32 mg/L and 3.96 mg/L, respectively. The performance of the method was evaluated on samples containing 25 mg/L and 400 mg/L of AMCC: each sample was analysed three times. The mean recovery of the extraction procedure was 88.3%. The precision (CV%) and the accuracy (Error%) ranged from 0.8% to 2.9%, and from -1.2% to +3.2%. The calibration curve was linear up to a concentration of 1000 mg/L, the coefficient of correlation was r = 0.9997. AMCC was measured in urine samples from 30 exposed and 20 unexposed (smokers and nonsmokers) subjects. Measurable amounts of AMCC were found in all of the samples from workers exposed to DMF; on the contrary, none of the samples from unexposed subjects contained this metabolite. The proposed method is sufficiently sensitive and specific for the evaluation of occupational exposure to DMF, thus it could be useful for the biological monitoring of workers exposed to this solvent.
N,N - 二甲基甲酰胺（DMF）是一种广泛用于制备合成纤维的溶剂。对DMF的生物监测通常通过测量尿中的N - 甲基甲酰胺来进行，这使我们能够估计工作日期间的接触情况。另一种生物标志物是硫醚氨酸N - 乙酰 - S -（N - 甲基氨基甲酰）半胱氨酸（AMCC），其排泄量约占吸收的DMF剂量的13%。由于其排泄缓慢（平均半衰期 = 23小时），工作周结束时尿中AMCC的水平反映了整个星期DMF的累积剂量。文献中给出的测量AMCC的方法在分析前需要对分子进行衍生化。本文描述了一种通过高效液相色谱（HPLC）直接紫外检测测定尿中AMCC的方法。样品用C18和ENV + 柱进行固相萃取纯化，然后将10微升直接注入保持在37℃的Aminex HPX - 87H离子排斥柱上。采用等度洗脱，以0.85 mL/min的流速输送1 mM硫酸进行分析。检测器设置在196 nm。在这些条件下，AMCC在11.1分钟时洗脱，检测限和定量限分别为1.32 mg/L和3.96 mg/L。该方法的性能在含有25 mg/L和400 mg/L AMCC的样品上进行了评估：每个样品分析三次。萃取过程的平均回收率为88.3%。精密度（CV%）和准确度（误差%）范围分别为0.8%至2.9%和 - 1.2%至 + 3.2%。校准曲线在浓度高达1000 mg/L时呈线性，相关系数r = 0.9997。在30名暴露和20名未暴露（吸烟者和非吸烟者）受试者的尿样中测量了AMCC。在所有暴露于DMF的工人的样品中都发现了可测量量的AMCC；相反，未暴露受试者的样品中均未含有这种代谢物。所提出的方法对于评估职业性DMF暴露具有足够的灵敏度和特异性，因此对于接触这种溶剂的工人的生物监测可能是有用的。
