石墨炉原子吸收法分析食醋中镉测定条件的响应曲面法优化

Response Surface Methodology for Optimization of Operating Conditions for Cadmium Determination in Table Vinegar by Graphite Furnace Atomic Absorption Spectrometry

利用响应曲面法对食醋中镉的测定条件进行优化。在单因素试验基础上,选取磷酸二氢铵质量浓度、灰化温度和原子化温度为自变量、吸光度为响应值,根据Box-Benhnken试验设计原理,采用三因素三水平响应曲面设计对吸光度进行回归分析,模拟得到二次多项式回归方程的预测模型。结果确定最佳测定条件为磷酸二氢铵质量浓度4.24mg/mL、灰化温度1013℃、原子化温度1921℃,在此条件下,测定食醋中镉的质量浓度为0.188μg/mL,与模型预测值基本相符,加标回收率为98.76%,相对标准偏差为2.68%。表明该方法可应用于实际样品测定。

Response surface methodology was employed to optimize three operating conditions for cadmium determination in table vinegar by graphite furnace atomic absorption spectrometry（GFAAS）.On the basis of one-factor-at-a-time experiments,absorbance at 228.8 nm of tested samples was modeled against NH4H2PO4 concentration,ashing temperature and atomization temperature using a three-variable three-level Box-Benhnken experimental design combined with multiple regression analysis.The built regression model was analyzed by response surface methodology.It was found that the optimal determination conditions were 4.24 mg/mL NH4H2PO4 concentration,ashing 1013 ℃,and atomization at 1921℃.Under these conditions,the predicted values showed a good agreement with the experimental values.Using the optimized GFAAS method,the content of cadmium in a commercial vinegar sample was determined to be 0.188 μg/mL with a spike recovery of 98.76% and a relative standard deviation of 2.68%.