Investigation of Pb in Gannan Navel Orange with Contaminant in Controlled Conditions by Laser-Induced Breakdown Spectroscopy

Abstract

Single-pulse laser-induced breakdown spectroscopy (LIBS) was applied at natural atmosphere for proving its feasibility of determining heavy metals in Gannan Navel orange fruits treated with contaminant in controlled lab conditions. The characteristic spectral line Pb I 405.78 nm was selected, and the LIBS experimental conditions (mainly the laser energy and delay time) were optimized in order to acquire better spectral quality in the measured spectra of orange peels. The conventional elemental analysis technique, atomic absorption spectrometry (AAS), was used to investigate the real concentration of orange peels samples. The results of AAS analysis provided better accuracy and precision compared with LIBS. A calibration curve of the LIBS intensity vs AAS concentration of Pb element was constructed. Quantitative analytical results obtained by the curve were validated with AAS measurements. The presented results showed that standard deviations of the LIBS measurements are in general much larger than those of AAS measurements. Mostly, this was due to the matrix effect of samples and instability of LIBS. The agreement between LIBS and AAS demonstrates the ability of LIBS to determine the concentration of Pb in oranges.