DDTC-火焰原子吸收光谱法同时测定铝合金中的铜和铅

DDTC-FAAS Simultaneous Determination of Copper and Lead in Aluminum Alloys

以铜空心阴极灯作为光源，用火焰原子吸收光谱法（FAAS）同时测定铝合金中的铜和铅。在氢氧化钠介质中，采用氯化镧和碳酸钠共沉淀，实现了铝合金中铜和铅与基体的分离。分离出来的沉淀用浓硝酸溶解，再加入过量的二乙基二硫代氨基甲酸钠（DDTC—Na），使其形成不溶的Cu（DDTC）2和Pb（DDTC）2，用三氯甲烷萃取后首先在435nm波长下进行FAAS（铅在此波长无吸收）测定得铜的含量，再加入过量的Cu（II）将Pb（Ⅱ）从Pb（DDTC）：中置换出来，此时再在相同波长下测定有机相中铜的吸光度，增加的吸光度的值即为铅的含量。本法简单快速，一次处理样品且不需要更换空心阴极灯即可同时测定两种元素。本方法铜和铅的线性范围分别为0．2—12ug／ml和0．2—13ug／ml，相关系数分别为0．9998和0．9997，回收率分别为98．91—102．91％和99．02-101．94％，测定下限分别为4．2×10^-6和5．0×10^-6，准确度和精密度完全能满足工业分析要求。

Copper hollow cathode lamp was used as light source in the flame atomic absorption spectrometry（FAAS） simultaneous determi- nation of copper and lead in aluminum alloys. The sample was dissolved in NaOH, lanthanum chloride and sodium carbonate were used as copre- cipitating agents, therefore copper and lead separated from aluminum alloy was achieved. The precipitation was dissolved in concentrated HNO3, then excess sodium diethyldithiocarbamate ＂（Na-DDTC） was added into the solution and water insoluble products of Cu（DDTC）2 and Pb（DDTC）2 were formed, which were extracted with the addtion of CHC13. The absorbance of the organic portion was measured at 435nm（lead has no absorp- tion at this wavelength） by FAAS, which is equivalent to copper content. Excess Cu（ II ） solution was added when lead was replaced from Pb（DDTC）2 immediately. The organic portion was further measured at the same wavelength, the additional absorbance is equivalent to lead con- tent. It is simple and rapid, only once sample processing was needed and simultaneous determination of copper and lead can be achieved without exchanging the hollow cathode lamp. Linear calibration range in this method was 0.2-12ug/ml for copper and 0.2-13ug/ml for lead with the re- gression coefficient 0.9998 and 0.9997 respectively, the recovery values were 98.91-102.91% and 99.02-101.94% for each, the limit of quantifi- cation were 4.2 × 10-6 and 5.0 × 10-6 respectively, so that the accuracy and precision can fully meet the requirements of industry analysis.