Improving Analytical Performance of Laser-induced Breakdown Spectroscopy for Strontium, the Minor Impurity Element, in Salts Using Multiple Filter-Paper Sampling

Abstract

Strontium (Sr) is an element of toxicological concern due to its close chemical proximity to Ca. In this work, Sr in sea salts collected from China and South Korea was analyzed by laser-induced breakdown spectroscopy (LIBS). The precision could be improved by using multiple filter-paper sampling and intensity normalization using a weak Na I line as a reference signal. The analyte signal variation between filter-paper pieces as well as that within a single filter-paper piece could be corrected by the suggested method. The limit of detection of ~2 ppm and the precision of ~5% could be obtained. As a measure of accuracy, the root-mean-square error was estimated to be 9 ppm. The multiple filter-paper sampling can be performed easily on the salt production sites and improves the LIBS analysis precision resulting to sufficient quantification capability for minor metallic elements in edible sea salt products.