基于RSM模型对石墨炉原子吸收法分析痕量金测定条件的优化研究

石墨炉原子吸收光谱法分析地球化学样品中痕量金的分析方法已被广泛应用，然而其测定条件及升温程序参数的配置在实际应用中难以匹配到合适的参数，因而快速且准确地寻找并确定有效参数具有重要的实践意义。试验以灯电流、灰化温度和原子化温度为自变量进行单因素试验，确定其试验参数范围分别为6～8 mA, 300～500℃和2 200～2 400℃;根据响应曲面法(RSM)建立Box-Behnken方法试验，采用三因素三水平曲面设计对响应值(吸光度)的影响进行分析，制作显著水平表并完成响应曲面试验；建立二次多项式回归方程的预测模型并进行显著性分析，其F=43.95,p<0.000 1表明该模型具有高度的显著性，模型的相关系数为0.985 1,校正决定系数为0.962 6,表明该模型可以解释超过95%的响应值变化；绘制响应曲面图和等高线图对试验数据进行回归拟合，通过响应曲面的形状和等高线的陡峭程度进行判定分析，最终寻找最优化参数为灯电流7.12 mA、灰化温度412.32℃和原子化温度2 311.61℃。结果表明，在最优化条件下测定国家一级标准物质GBW07246a的平均吸光度为0.101 2,与模型...

Research on Optimization of Determination Conditions for Trace Gold Analysis by Graphite Furnace Atomic Absorption Spectrometry Based on RSM Model

The analytical method of trace gold in geochemical samples by graphite furnace atomic absorption spectrometry(GFAAS) has been widely used. However, it is hard to figure out the appropriate matching parameters in practice in terms of the configuration of its determination conditions and temperature-rising program parameters. Due to this reason, it is of great practical significance to work out effective parameters quickly and accurately. The single factor test is carried out with lamp current, ashing temperature, and atomization temperature as independent variables and its parameters are set to be 6~8 mA, 300~500 ℃ and 2 200~2 400 ℃ respectively; The Box-Behnken test is done according to the Response Surface Methodology (RSM). The influence of three-factor and three-level surface design on the response value (absorbance) is analyzed; the significance level table is prepared, and the response surface test is completed; a prediction model of the quadratic polynomial regression equation is built analyze the significance. F=43.95, p<0.000 1 means that the model has high significance with its correlation coefficient of 0.985 1.Thefact that the correction coefficient of determination is 0.962 6 indicates that the model can explain more than 95% of the changes in response values; the response surface and contour map are drawn to regress and fit the test data. Judgement and analysis are made according to the shape of the response surface and the steepness of the contour. These optimal parameters as lamp current 7.12 mA, ashing temperature 412.32 ℃, and atomization temperature 2 311.61 ℃ are worked out. The results suggest that under an optimized condition, the average absorbance of national first-class reference material GBW07246a is 0.101 2, basically consistent with the predicted value of 0.108 0, and the relative error remains 6.30%; six national first-class reference materials, including GBW07243b are selected for 12 repeated tests, and the standard curve is drawn, and the results are read. The logarithmic deviation between the average value and the standard value of each reference material is less than 0.05, the relative standard deviation (RSD, n=12) is less than 10%, and both the accuracy and precision comply with GB/T 27417—2017 (Guide for confirmation and verification of chemical analysis for conformity assessment), indicating that the parameters of conditions for the determination of trace gold by graphite furnace atomic absorption spectrometry based on RSM model are accurate and reliable, which proves the correctness and feasibility of this model and achieves a good optimization result. This method is expected to be applied to determine and analyze other elements and in the method research of instrument analysis platform to find the optimal analysis and test conditions.