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    塑料制品中铅、汞、镉、铬(Ⅵ)测定

    Determination of Lead Mercury Cadmium and Chromate in Plastics

    • 摘要: 塑料样品用硝酸、盐酸、高氯酸及过氧化氢(含硅样品尚须加入氢氟酸)加压消解,可按程序用微波加热或置于不锈钢压力罐中,密闭后在控温于190 ℃的烘箱中加热.所得试样溶液供电感耦合等离子体原子发射光谱法测定铅、汞及镉,要求及限量的盐酸抵消氯离子的影响,测定了标准物质中铅、汞、镉的含量,测得结果与证书值一致,铅、汞、镉测定值的相对标准偏差(n=9)在0.3%~8.0%之间.另取样品用二苯基羰酰二肼(DPC)光度法测定其铬(Ⅵ)含量,样品中铬(Ⅵ)用氢氧化钠-碳酸钠混合溶液和磷酸二氢钾-磷酸氢二钾缓冲溶液超声提取60 min,分取部分过滤提取液,按DPC光度法测定铬(Ⅵ)量.测得铬(Ⅵ)的平均回收率为95%,平均相对标准偏差(n=9)为0.35%.铅、汞、镉及铬(Ⅵ)的检出限(3σ)依次为0.011,0.007,0.003,0.001 mg·L-1.

       

      Abstract: Plastics sample was digested with HNO3,HCl,HClO4 and H2O2 (also with HF for silica-containing sample).The heating process was performed either in a microwave oven or in a drying oven at 190 ℃.The sample solution obtained was used for the ICP-AES determination of lead,mercury and cadmium.Same and limited amounts of HCl were added,to compensate for the interference of chloride ion to the determination of mercury.CRM′s were analyzed by the proposed method,giving values of contents of Pb,Hg and Cd in consistency with the certified values,and values of RSD′s (n=9) in the range of 0.3%-8.0%.Hexavalent chromium (CrO2-4) was determined on a separate sample by the diphenyl carbazide (DPC)-photometric method.Hexavalent chromium was extracted from the sample by solution mixtures of NaOH+Na2CO3 and K2HPO4+KH2PO4.An aliquot of filtrate from the extract was taken and its Cr(Ⅵ) content determined by the DPC-photometry.Recovery of Cr(Ⅵ) was tested by addition of standard solution of Cr(Ⅵ) to PVC samples,values of av.recovery and av.RSD′s (n=9) found were 95% and 0.35% respectively.Detection limits (3σ) found for Pb,Hg,Cd and Cr(Ⅵ) were 0.011,0.007,0.003 and 0.001 mg·L-1 respectively.

       

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