Determination of toxic elements in glass beads used for pavement marking by ICP OES

A simple and rapid method for the simultaneous determination of As, Sb and Pb in glass beads used for pavement markings on highway surfaces by axial view inductively coupled plasma optical emission spectrometry is presented. Three sample preparation approaches using a 3:1 mixture of HNO3 and HF were evaluated: (01) an open beaker approach; (02) a microwave-assisted digestion system, based on EPA method 3052 and (03) an ultrasound-assisted digestion. To react with the excess of residual fluoride, H3BO3 and ZrOCl2 were investigated. Spectral interference was evident when ZrOCl2 was used for determination of As. Ultrasound-assisted digestion using 3 mL of HNO3 and 1 mL of HF for 1 h at 40 kHz followed by addition of H3BO3 was chosen for in-depth study. Quantification limits (10 s, n = 10) based on a 0.1 g subsample diluted to 50 mL were: 30 mg kg− 1 for As (193.696 nm), 10 mg kg− 1 for Sb (206.834 nm) and 5 mg kg− 1 for Pb (220.353 nm). Analysis of spiked samples provided recoveries in the range of 87 to 104% for all analytes. Of nineteen Brazilian and imported samples analyzed, As was present above the quantification limit in five, Sb in one and Pb in almost all. Some samples, all imported, showed values above the limit allowed by the Brazilian legislation, i.e., 200 mg kg− 1 for As, Sb and Pb. Solubility tests showed high levels of As leaching for all imported samples, above the specification limit. Leachability tests showed that the glass beads cannot be classified as toxic materials; however, the release of potentially toxic elements could cause some environmental risks.