建立了微波等离子体原子发射光谱(microwave plasma atomic emission spectroscopy, MP-AES)测定食用坚果油中金属元素含量的分析方法。食用坚果油经微波消解法预处理后直接利用MP-AES测定其中的8种金属元素Na、Mg、K、Cu、Fe、Zn、Mn、Ba。通过选择各元素合适波长的分析谱线消除了光谱干扰,选择Y、La、Lu为内标元素消除了物理干扰,采用加标回收实验并应用电感耦合等离子体质谱(inductively coupled plasma mass spectrometry, ICP-MS)法进行对比分析验证方法的准确性。结果表明,各元素的线性关系良好,线性相关系数≥0.999 2,方法的检出限(method detection limit, MDL)为0.02~0.12 μg/g,加标回收率为90%~110%,相对标准偏差(relative standard deviation,RSD)≤5.9%,采用MP-AES测定实际样品的分析结果与ICP-MS基本一致。所建立的方法简单快速、准确可靠,为食用坚果油中Mg、Na、K、Cu、Fe、Zn、Mn、Ba含量的测定提供了方法学手段。
A analytical method to determine metal elements in edible nut oil by microwave plasma atomic emission spectroscopy (MP-AES) was proposed. After the pretreatment of edible nut oil sample by microwave, the eight metal elements including Na, Mg, K, Cu, Fe, Zn, Mn and Ba in the digestion solution were determined by MP-AES. The spectral interference was eliminated by selecting the appropriate wavelength of analyte as the analysis line. The physical interference was eliminated by selecting Y, La, Lu as internal standard elements. The accuracy of the method was evaluated by spiked recovery experiment combined with inductively coupled plasma mass spectrometry (ICP-MS) comparative analysis. The results showed that the linear relationship of analyte was good and the linear correlation coefficient was ≥ 0.999 2. The method detection limit (MDL) was 0.02-0.12 μg/g, the spiked recovery was 90%-110%, and the relative standard deviation (RSD) was less than 5.9%. The MP-AES was used to test the actual samples and the analytical results were consistent with ICP-MS. The method is simple, rapid, accurate and reliable, which provides methodological method for the determination of Mg, Na, K, Cu, Fe, Zn, Mn and Ba in edible nut oil.
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