Metals and Metalloids in Different Size Fractions of Printed Circuit Boards by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)

Over the last half century, the increase in the world population and the well-being of those living in the most advanced nations, together to the escalation in acquisition of electrical and electronic devices, have led to a growth in electronic waste (WEEE). In this study five granulometric fractions obtained from computers mother boards were investigated to quantify 25 elements. Inductively coupled plasma emission spectrometry (ICP-OES) and Inductively coupled plasma mass spectrometry (ICP_MS) are the most employed multi-elemental analytical techniques to quantify several elements in a large concentration range in complex environmental and food matrices [1, 2] as in the solution obtained from the treatment of electronic waste or from others [3, 4]. In our case, after mineralization by microwave, using a mixture of strong acids and hydrogen peroxide, the ICP-OES technique was used. One of the benefits of this method is the low detection and quantification limits which can be particularly relevant for elements present at trace levels. In fact, the LOQ values referred to the solid sample, ranged from 4·10-5 to 5·10-3 %. Copper is the main element of printed circuit boards (8.5 to 26%), aluminium is the second (2.5 and 6.1%), while tin (0.1÷1.6%), lead (0.4÷1.2%) and antimony (0.1÷0.4%) probably devise from the alloys used in soldering. Ni (0.01÷0.7%) probably comes from the plating of the pins that connect the various devices. Au (0.01÷0.03%) and Ag (0.02÷0.2%) may also have had the same origin since they are used in the most expensive and efficient motherboards. Zinc (0.4÷15.0%) is the fourth most abundant metal. Figure shows the Distribution of single elements in the different granulometric fractions. Taking into account the percentages and the value of the main precious elements in the electronic waste, as those analysed by us, the rational and organized recovery of the aforementioned material could lead to a non-negligible economic profit and the protection of the environment and the health of workers. References: [1] F. Di Gaudio, D. Amorello, M. Ferrara, S. Orecchio, S. Orecchio, Heavy Metals in Tattoo Inks: Developing an Analytical Methodology for Accessing Customer Safety, ChemistrySelect, 8 (2023) e202300986. [2] S. Barreca, S. Orecchio, S. Orecchio, I. Abbate, C. Pellerito, Macro and micro elements in traditional meals of Mediterranean diet: Determination, estimated intake by population, risk assessment and chemometric analysis, Journal of Food Composition and Analysis, 123 (2023) 105541. [3] S. Orecchio, Microanalytical characterization of decorations in handmade ancient floor tiles using inductively coupled plasma optical emission spectrometry (ICP-OES), Microchemical Journal, 108 (2013) 137-150. [4] M.R. Mannino, S. Orecchio, Chemical characterization of ancient potteries from Himera and Pestavecchia necropolis (Sicily, Italy) by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES), Microchemical Journal, 97 (2011) 165-172.