Quantitative Analysis of Cr in Milk Powder by Laser Induced Breakdown Spectroscopy （LIBS）
摘要
At present,heavy metal pollution in food occurs frequently,which requires a novel method for rapid detection. Laser induced breakdown spectroscopy( LIBS) is a new technique for rapid and environmental friendly detection,but it lacks high sensitivity and stability which restrict its development. In this study,Cr-polluted infant milk powder was used as experimental material to explore the feasibility of the application of LIBS technique in food safety detection. Aiming at improving the precision and accuracy of Cr detection by LIBS technique,LIBS spectra of samples were collected by a spectrometer with an intensified charge-coupled device( ICCD) using three gratings with different resolutions to comprehensively compare and analyze the stability,sensitivity and quantitative analysis accuracy of LIBS detection. The results showed that average relative standard deviation( RSD) of LIBS spectral intensity was below 10%,indicating good stability. LIBS signals were collected by three gratings for quantitative analysis,and the results demonstrated that the linear correlation coefficient R~2 of fitting curves was0. 248 87,0. 903 12 and 0. 992 81,respectively; the relative errors between actual and predicted concentrations were 38. 23%,8. 84% and 7. 43%,respectively,indicating that gratings with higher resolutions could lead to higher linear correlation coefficient and better detection accuracy. According to the results,high-resolution spectrometer could significantly improve the accuracy of LIBS detection of Cr concentration in milk powder,suggesting that it is feasible to detect heavy metals in food by LIBS technique with the improvement of core device performance.