Assessment of Cd, Cu, Pb, and Zn concentrations in leather by ICP-MS: a multivariate analysis of an eco-friendly approach

Abstract

ABSTRACT Due to the metal-complex dyes used in tannery industries, potentially toxic metals can be present in leather. However, publications regarding metal determination in leather are scarce, and most sample preparation procedures are still time-consuming. Therefore, a simple and straightforward sample preparation approach using ultrasound-assisted extraction (UAE) was proposed for the determination of Cd, Cu, Pb and Zn in leather samples by ICP-MS. A full factorial design 23 was used to investigate the extraction conditions. Fitted conditions were obtained at a ratio of 100 mg: 1.0 mL (sample:HNO3 14.0 mol L−1), ultrasound-assisted extraction time of 55 min at 75 ± 3°C. The method´s accuracy was evaluated through the comparison of results with those obtained using microwave-assisted digestion (MWAD) approach. The UAE results were statistically similar to the MWAD, according to the Student t-test (α = 0.05) and linear regression analysis. Limits of detection (LOD), at mg kg−1 range, and method precision (RSD <11%) were suitable for the analytes´ determination in leather. The proposed method was successfully applied to analyse 18 different leather samples. The results were < 0.3 to 53.19 mg kg−1 for Cd, <0.2 to 484.61 mg kg−1 for Cu, <0.02 to 211.31 mg kg−1 for Pb and < 0.02 to 379.22 mg kg−1 for Zn, respectively. The proposed method is simple and faster than the traditional acid digestion sample preparation. Moreover, according to green analytical chemistry, the method scored 82 points on the Eco-Scale, confirming the proposed method as environmentally friendly.