石墨炉原子吸收法直接测定龙骨水煎液中Cr（Ⅵ）的方法研究

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pH 5.7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Cr^Ⅲ（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 a method for the direct determination of chromium (Ⅵ) by graphite furnace atomic absorption spectrometry (GFAAS). Methods: The trifluoroacetylacetone (TFA) buffer solution was obtained by mixing TFA with cyclohexane;then the buffer of acetic acid-sodium acetate was added;the volume ratio of these three agents were 1:2:2.Cr(Ⅲ) reacted with TFA in water bath at 70 ℃ to form a volatilizable chelate Cr^Ⅲ(TFA)₃ which was volatilised totally in the GFAAS procedure in order to separate chromium (Ⅲ) and chromium (Ⅵ);then the concentration of chromium (Ⅵ) was obtained. Results: The linearity of this method ranged from 0 to 100 ng·mL^-1;the calibration curve was Y=5.593×10^-3X+7.524×10^-3;the correlation coefficient was 0.9999;the average spiked recoveries were 98.0%,100.9%,104.5% at low,medium and high concentrations,respectively; RSD of precision test was 0.58%. Conclusion: This method is accurate,simple,feasible and rapid,which met the analytical requirement and could be used for the determination of chromium (Ⅵ) in Os.Dracoins decoction.