Assessment of potentially toxic elements in vegetables and soil samples irrigated with treated sewage and human health risk assessment

Abstract

In this work, a new microextraction approach termed as vortex-assisted liquid phase microextraction based on deep eutectic solvent (VALPME-DES) combined with graphite furnace atomic absorption spectrometry (GFAAS) has been developed for the extraction, preconcentration and determination of potentially toxic elements (PTEs) in vegetables and soil samples irrigated with treated sewage from two different regions of Iran. The new DES was prepared by mixing a 1:1 molar ratio of choline chloride and citric acid monohydrate. Some effective parameters on extraction were studied and optimised. Under the optimum conditions, the repeatability and reproducibility of the VALPME-DES coupled with ETAAS for 5.0 µg L−1 of As(III) and 0.50 µg L−1 of Pb and Cd were determined to be 2.7–4.3 and 3.8–6.2%, respectively. The correlation coefficient (r2) of the calibration curves was in the range of 0.995–0.998. The limit of detections was in the range of 0.03 and 0.1 µg kg−1 for different metal ions. Linear range of 0.3 − 100 µg kg−1 for As(III) and, 0.03–200 µg kg−1 for Cd and Pb were obtained. The results showed among the target metals, the highest impact on the total value of non-carcinogenic risk was related to arsenic. Furthermore, the non-carcinogenic risk value for all vegetable types was lower than the permitted level. We also found that the risk of arsenic carcinogenicity was higher than the acceptable levels in all four types of vegetables. According to the findings, interventions to reduce arsenic should be used, especially in cultivated soils.