ICP-MS测定铅同位素比值及不同样品间铅同位素比值的比较
Determination of lead isotope ratios by inductively coupled plasma mass spectrometry and comparison of lead isotope ratios among different samples
-
摘要:
背景 不同来源的铅同位素比值（LIR）不同。国内外关于人血或尿LIR溯源的报道，主要集中在对同一个体或不同个体间血样、尿样的比较，较少进行生物样品与环境样品间的比较，且主要LIR（207/206Pb、208/206Pb）测定精密度（RSD）的波动较大，在0.3~1%之间。
目的 优化电感耦合等离子体质谱法（ICP-MS），以获得更好的RSD，并对人体血、尿及相关环境样品LIR进行测定和分析。
方法 优化ICP-MS的运行参数和采集参数，主要根据LIR测定的灵敏度和RSD来进行参数的确定。以铅蓄电池厂40名工人和医院2名铅中毒儿童为研究对象，收集班前接铅工人的血样40份、尿样40份，同一天班前的工作场所降尘样品4份、工厂自来水水样2份，铅中毒儿童入院时的血样2份、入院时的尿样3份及治疗后的尿样4份。对样品进行加热酸解处理，应用优化的ICP-MS方法测定研究对象的生物样品和环境样品的主要LIR（207/206Pb、208/206Pb），并运用
t 检验、二维图形分析方法对测定结果进行分析。结果 校准后的铅同位素标准溶液的LIR（207/206Pb、208/206Pb）的RSD分别为0.11%、0.08%，NIST-SRM-981实测值为0.91531±0.00097、2.1670±0.0017。当总铅质量浓度大于5 μg·L−1时，各同位素比值的RSD逐渐稳定；当总铅质量浓度在10 ~80 μg·L−1时，各同位素比值的RSD均小于0.20%。接铅工人血、尿LIR（207/206Pb、208/206Pb）分布的差异存在统计学意义（
t =5.831，P <0.001；t =21.021，P <0.001）；车间降尘与尿样之间的LIR（207/206Pb、208/206Pb）分布的差异也存在统计学意义（t =−6.879，P =0.038；t =12.521，P <0.001）；车间降尘与血样的207/206Pb分布的差异无统计学意义（t =−0.12，P =0.912），但208/206Pb分布的差异存在统计学意义（t =−10.46，P <0.001）。铅中毒患者中，同一个体血、尿样的LIR在二维模型中的投射点不在同一水平上，驱铅治疗前后同一个体尿样LIR在二维模型中的分布也不在同一水平。结论 本研究优化后的ICP-MS法可将主要LIR（207/206Pb、208/206Pb）的RSD控制在0.20%以下。不同样品的LIR分布之间存在差异。
Abstract:background The lead isotope ratios (LIR) differ among different sourced samples. Previous domestic and oversea studies on source tracing by LIR in human blood or urine mainly focused on the comparison of blood or urine samples from the same or different individuals, while few comparisons between biological and environmental samples, and the reported relative standard deviations (RSDs) of the main LIR (207/206Pb and 208/206Pb) fluctuate widely from 0.3% to 1%.
Objective To optimize inductively coupled plasma mass spectrometry (ICP-MS), obtain a better RSD, and determine LIRs of human blood, urine, and related environmental samples.
Methods The ICP-MS was optimized for operating conditions and parameters according to the sensitivity and RSD of LIR. The study subjects were 40 lead-exposed workers in a lead-acid battery factory and 2 lead poisoned children in a hospital. The samples included 40 blood and 40 urine samples from the workers before shift, 4 dust samples and 2 water samples in the workplace on the same day before shift, 2 blood and 3 urine samples from the children before hospital admission due to lead-poisoning, and 4 urine samples after medical treatment. After heating and acid digestion, the LIR (207/206Pb and 208/206Pb) of biological and environmental samples were determined by the optimized ICP-MS method.
t -test and two-dimensional traceability graphics were adopted to analyze the detection results.Results The calibrated RSDs of the LIR (207/206Pb and 208/206Pb) of lead isotope standard solution were 0.11% and 0.08% respectively, and the NIST-SRM-981 actual values were 0.91531±0.00097 and 2.1670±0.0017, respectively. When the total concentration of lead was greater than 5 μg·L−1, the RSD of each isotope ratio was stable gradually; when the total concentration of lead was between 10-80 μg·L−1, the RSD was below 0.20%. There were statistically significant differences in the blood and urine LIR (207/206Pb and 208/206Pb) of the lead-exposed workers (
t =5.831,P <0.001;t =21.021,P <0.001), the LIR (207/206Pb and 208/206Pb) between workplace dust samples and workers’ urine samples (t =−6.879,P =0.038;t =12.521,P <0.001), and the 208/206Pb between workplace dust samples and workers’ blood samples (t =−10.46,P <0.001), except the 207/206Pb between workplace dust samples and workers’ blood samples (t =−0.12,P =0.912). In the patients afflicted with lead poisoning, the projection points of LIR of blood and urine samples from the same individual were not at the same level in the two-dimensional model, nor was the LIR of urine samples before and after medical treatment of the same individual.Conclusion The optimized ICP-MS can control the RSD of main LIR (207/206Pb and 208/206Pb) below 0.20%. There are differences in the LIR distributions of different samples.
下载:
