Microwave induced plasma optical emission spectrometry (MIP OES) and laser-induced breakdown spectroscopy (LIBS) for multi-element determination and location in ceramic tableware

Abstract

In the present study, the microwave induced plasma optical emission spectrometry (MIP OES) and laser-induced breakdown spectroscopy (LIBS) complementary techniques are used to determine and locate metals in ceramic tableware samples. For quantitative analysis by MIP OES, a new method for sample treatment is proposed, preparing the samples using ultrasonic decomposition aided by an acid mixture containing HNO3 and HF. The highest average concentrations were found in the group of Brazilian samples for most of the analytes. The accuracy of the quantitative method was assessed by comparing the results with two methods described in the literature. No significant differences were detected. Aiming at qualitative analysis and analyte locating by LIBS, a sample fragment was already sufficient for the analysis, being possible to observe that Al, Ba, Ca, Fe, K, Li, Mg, Na and Ti are present in the ceramic mass and decorated surface, while Cd, Co, Cr, Cu, Mn, Pb and Zn are found only on the sample surface. Besides, according to LIBS results, it would be essential to pay attention to pigmentation, which contains most of the potentially toxic elements, at locations in direct contact with food to minimize the risk of leaching and avoid human contamination. This study shows that MIP OES and LIBS can be used complementarily to improve the analytical information used to control the ceramic tableware quality and safety. The conclusions of this work can be extended to several other types of samples where both the average contents and the location of the elements are relevant.