同位素稀释质谱法测定国际比对样品Sn-Ag-Cu系焊锡中的铅

将²⁰⁷Pb同位素稀释剂与样品混合，加入H₂O₂和HF对混合样品进行消解，采用同位素稀释质谱法对两种不同铅含量国际比对焊锡样品中的铅进行了测定。使用常规硝酸和盐酸消解Sn-Ag-Cu系焊锡时易生成氯化银和β-锡酸不溶物的H₂O₂-HF体系避免了此类问题，并加快了样品消解速度。研究了样品基体对²⁰⁸Pb/²⁰⁷Pb比值测定及最终结果的影响，在保证精密度的情况下，通过逐级稀释的方式可降低测定过程中大量锡基体的干扰。建立了Sn-Ag-Cu系焊锡中高、低含量铅的准确测定方法，并对测定结果的不确定度进行了评定。CCQM-P119和CCQM-K88“无铅焊锡”中铅的国际比对结果表明，同位素稀释质谱法与传统方法相比，准确度高、不确定度小，测定结果获得了很好的等效度，从而进一步验证了方法的准确性和可靠性。该方法同样适用于焊锡基体标准物质的定值。

Determination of Lead in Sn-Ag-Cu Solder for CCQM Comparisons by IDMS

The contents of two levels of lead in Sn-Ag-Cu system solder for CCQM comparisons were determined by isotope dilution mass spectrometry (IDMS) after the samples were mixed with ²⁰⁷Pb spike and digested by H₂O₂-HF in PTFE vessel. H₂O₂-HF digestion system avoided forming silver chloride and β-stannic acid when using conventional nitric acid and hydrochloric acid for Sn-Ag-Cu solder, and saved the digestion time. Matrix effects on ²⁰⁸Pb/²⁰⁷Pb ratio determination and the resulting Pb contents in solder were discussed, and the result shows matrix effect was reduced by selecting the appropriate dilution factor in the case of guaranteed precision. Established accurate determination method for high and low level of lead in Sn-Ag-Cu system solder, the uncertainty of the measurement was also analyzed and evaluated. The good degree of equivalence of CCQM-P119 and CCQM-K88 indicates IDMS has good accuracy and small uncertainty compared with traditional methods, it validate reliability of this method. The established IDMS method is suitable for the certification of similar solder reference materials.