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目的:建立石墨炉原子吸收法直接测定六价铬Cr(Ⅵ)的含量。方法:将三氟乙酰丙酮(TFA)和环己烷混匀,再加入pH5.7醋酸-醋酸钠缓冲溶液,三者体积比为1∶2∶2,制得TFA缓冲溶液,采用TFA作为螯合剂与Cr(Ⅲ)在70℃水浴中反应形成可挥发性螯合物CrⅢ(TFA)3,通过石墨炉升温程序使螯合物完全挥发,将Cr(Ⅲ)和Cr(Ⅵ)分离,测定Cr(Ⅵ)的含量。结果:线性范围为0~100 ng·mL-1,回归方程为Y=5.593×10-3X+7.524×10-3,r=0.9999,样品低、中、高浓度平均回收率分别为98.0%、100.9%、104.5%,精密度试验的RSD为0.58%。结论:本法操作简便,分析速度较快,满足分析测试要求,适于龙骨水煎液中Cr(Ⅵ)含量的测定。
Objective: To establish direct determination of hexavalent chromium Cr (Ⅵ) by graphite furnace atomic absorption spectrometry. Methods: Mix Trifluoroacetylacetone (TFA) with cyclohexane, then add acetic acid - sodium acetate buffer solution (pH5.7) at a volume ratio of 1: 2: 2 to obtain TFA buffer solution, using TFA as chelate Cr (Ⅲ) and Cr (Ⅲ) react with Cr (Ⅲ) to form volatile chelate Cr Ⅲ (TFA) 3 in water bath at 70 ℃. The chelate is completely volatilized by graphite furnace temperature increasing program. Cr (Ⅲ) and Cr Cr (Ⅵ) content. Results: The linear range was 0-100 ng · mL-1, the regression equation was Y = 5.593 × 10-3X + 7.524 × 10-3, r = 0.9999. The average recoveries of low, middle and high concentration samples were 98.0% 100.9%, 104.5%, RSD precision test 0.58%. Conclusion: The method is simple and easy to operate, the analysis speed is fast, and meets the requirements of analysis and testing. It is suitable for the determination of Cr (Ⅵ) in keel decoction.