Spark discharge-libs: Evaluation of one-point and multi-voltage calibration for p and al determination

Abstract

Spark discharge (SD) laser-induced breakdown spectroscopy (LIBS) is a technique suitable to overcome the low energies of lasers by reheating the plasma, increasing the emission intensities and to perform single-standard calibration. A calibration method called one-point and multi-voltage calibration (OP-MVC), which requires two different voltages applied to both the standard and the sample, is proposed for use with SD-LIBS. The performance of this method was compared to that of the one-point and multi-lines calibration (OP-MLC) and the slope ratio calibration (SRC) methods for LIBS determination of Al in certified reference plant leaves and P in commercial fertilizers. No statistical differences at the 95% confidence level were observed between the Al and P concentrations determined by OP-MVC LIBS for the Al certified values and the P values measured by high-resolution continuum-source flame atomic absorption spectrometry (HR-CS FAAS). The limit of detection (LOD) for P was 0.60 wt% P2O5 and 35.1 mg kg-1 for Al. The relative standard deviation (n=3) was typically 7% for Al and in the 4-10% range for P.