摘 要 ：为了寻求大豆油中铬(Cr)的快速检测方法,应用激光诱导击穿光谱(LIBS)技术对大豆油中Cr含量进行定量检测研究,采用松木对大豆油样品中的Cr进行富集,并利用双通道光谱仪采集其LIBS光谱信号;选择钙(Ca) 422.64 nm为内标线,并以Cr的原子谱线Cr I 425.44 nm、Cr I 427.48 nm、Cr I 428.94 nm及3条谱线之和为分析线,应用直接定标法和内定标法分别建立上述分析线的定标曲线。结果表明,Cr I 425.44 nm建立的定标曲线性能最佳,直接定标法和内定标法所建立的定标曲线的拟合度R2分别为0.9598和0.9894,检测限分别为14.82 μg·g-1和8.45 μg·g-1; 3个验证样品预测的相对误差分别为11.32%、12.78%、12.48% 和7.91%、4.28%、7.64%。由此可知,LIBS技术用于大豆油中重金属Cr的检测具有一定的可行性,松木富集结合内定标法能减少定量分析误差,提高大豆油中Cr含量的预测精度。本研究结果可为食用油中重金属的快速检测提供理论依据。
Abstract:In order to find a rapid method for chromium detection in soybean oil, laser-induced breakdown spectroscopy (LIBS) technique was used to detect chromium content in soybean oil quantitatively. Pine wood was used to enrich the Cr in soybean oil, then LIBS spectra of the samples were acquired by a two-channel spectrometer. Calcium (Ca) 422.64 nm was selected as the internal standard line, Cr I 425.44 nm, Cr I 427.48 nm, Cr I 428.94 nm and sum of the 3 spectral lines were used as analytical lines. Then, direct calibration and internal calibration methods were used to develop calibration curves of above analytical lines. The results indicate that the calibration curve using Cr I 425.44 nm has the best performance, the fitting degree (R2) of calibration curves developed by direct calibration and internal calibration methods are 0.9598 and 0.9894, and the detection limits are 14.82 μg·g-1 and 8.45 μg·g-1. The predicted relative errors of the three samples in two calibration curves are 11.32%, 12.78%, 12.48% and 7.91%, 4.28%, 7.64%, respectively. This shows that LIBS technology is feasible to detect heavy metals Cr in soybean oil, pine wood enrichment combined with internal calibration method can reduce the error of quantitative analysis, and improve prediction accuracy of Cr content in soybean oil. This research can provide theoretical foundation for heavy metal detection in edible oils.