微波消解-火焰原子吸收光谱法测定食品中痕量镍

Determination of Trace Nickel in Foods by Microwave Digestion Followed by FAAS

建立微波消解-火焰原子吸收光谱法测定食品中痕量镍的新方法。通过微波消解条件优化,确定最佳消解条件为浓硝酸-双氧水(4:1,V/V)为消解液,1.5MPa消解15min。通过实验介质、活化剂、仪器操作条件的考察,确定最佳分析条件。在pH4.7的醋酸-醋酸钠介质中及NP-10活化下,在仪器的最佳操作条件下,镍在3.1 10-6～4.8 10-4g/L范围内,吸光度与镍质量浓度遵循比尔定律。该方法的测定波长为232.6nm,检出限为3.1 10-6g/L。所建方法用于食品中痕量镍的测定,最大相对标准偏差为4.2%,加标回收率为95.1%～106.4%,所建方法与GB/T 5009.138—2003《食品中镍的测定》进行对比,方法相对误差不高于5.8%。

A microwave digestion-flame atomic absorbance spectrometry （FAAS） method was developed to determine trace nickel in foods. The optimal microwave digestion conditions were established as follow： concentrated nitric acid-hydrogen peroxide （4：1, V/V） as digestion solution, digestion time 15 min, and digestion pressure 1.5 MPa. Meanwhile, the optimal solvent medium, activator and instrumental conditions were determined. When present in pH 4.7 acetic acid-sodium acetate buffer, activated by NP-10, the relationship between absorbance and nickel concentration over the range of 3.1 ×10.6 4.8×10-4 g/L as detected under optimized instrumental conditions obeyed Beer＇s law. The detection wavelength was set at 232.6 nm. The limit of detection of this method was 3.1×10-6 g/L. The maximum precision RSD for 5 replicate determinations of nickel in cereal grains was 4.2% and average spike recoveries ranged from 95.1% to 106.4%. Compared with the method of GB/T 5009.138-2003, the maximum relative error was not higher than 5.8%.