Assessment of feasibility in determining of Cr in Gannan Navel Orange treated in controlled conditions by laser induced breakdown spectroscopy

Heavy metal element chromium (Cr) contained in Gannan Navel Orange fruits treated with contaminant in controlled lab conditions were analyzed by laser induced breakdown spectroscopy (LIBS) and atomic absorption spectrometry (AAS). The purpose of this work was to provide an assessment of the performance of LIBS in investigating heavy metals in natural organic materials through a direct comparison of the analytical results. The LIBS spectra of samples were collected by optimized experimental parameters and the characteristic spectral lines of two triplet bands at 357.87 nm, 359.35 nm and 360.53 nm and 425.43 nm, 427.48 nm and 428.97 nm were identified distinctly. The Cr I 425.43 nm was selected as analytical line. The concentrations of Cr element were determined by AAS. The relative standard deviation (RSD) values were analyzed and the results demonstrated that there are much more room to promote in LIBS measuring. The calibration curve between the LIBS intensity and AAS concentration was constructed about Cr element. The results show LIBS signal intensity linear dependence on the concentration of Cr. Quantitative analytical results by the curve were validated with MS measurements. The presented results showed that the standard deviations of the LIBS measurements are in general much larger than those of MS measurements. Mostly, this contributes to matrix effect of samples and instability of LIBS. In a word, the obtained results between LIBS and AAS demonstrate the capacity of LIBS in the determination of the concentrations of Cr in oranges. Further work are being continued in our laboratory for further improvement of the sensitivity of LIBS, and for direct analysis of heavy metals in natural agricultural products without contamination treatment. (C) 2013 Elsevier Ltd. All rights reserved.