Department of Molecular Science and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, I-30172, Venezia, Mestre, Italy.
Department of Molecular Science and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, I-30172, Venezia, Mestre, Italy.
Talanta. 2020 Apr 1;210:120667. doi: 10.1016/j.talanta.2019.120667. Epub 2019 Dec 23.
In this paper we present a novel combined electrochemical-spectroscopic approach suitable to monitor trace levels of heavy metals directly in edible oils. The method is based on the electrochemical preconcentration/extraction of the analyte from the tested real matrix by cathodic deposition onto a Pt working electrode, then transfer and anodic re-oxidation of the metallic deposit to a "clean" aqueous solution, suitable for the subsequent spectroscopic analysis. The procedure has been here focused to the determination of lead in extra virgin olive oil (EVOO), performed by applying ICP-QMS or GFAAS techniques. To this aim, the EVOO samples were mixed with proper amounts of the room temperature ionic liquid (RTIL) [P][NTf], in order to obtain a non-aqueous supporting electrolyte suitable for the electrodeposition process. The feasibility and performance of the analytical strategy were at first tested in standard solutions of Pb(II) in RTIL, produced by anodic dissolution of lead in the RTIL, as well as in olive oil samples mixed with 0.5 M RTIL and spiked with known amounts of Pb(II). The optimisation of the electrochemical parameters was achieved by applying a D-Optimal Design, properly set up to optimise the efficiency of the deposition and re-oxidation steps, quantitative recovery and measurement time. Finally, the analytical procedure was applied to the determination of Pb content in some Italian EVOOs, without any need of performing mineralization pretreatments. Data obtained with the proposed procedure satisfactorily agree with those achieved by ICP-QMS analysis after microwave digestion, being differences between the two approaches within 10%, with the advantage of reducing to half the pretreatment time, operating at room temperature and avoiding the use of aggressive solvents.
本文提出了一种新颖的电化学-光谱组合方法，适用于直接监测食用油脂中的痕量重金属。该方法基于电化学从测试的实际基质中预浓缩/萃取分析物，通过阴极沉积到 Pt 工作电极上，然后将金属沉积物转移并在“清洁”水溶液中阳极重新氧化，以便随后进行光谱分析。该程序专注于通过 ICP-QMS 或 GFAAS 技术测定特级初榨橄榄油 (EVOO) 中的铅。为此，将 EVOO 样品与适量室温离子液体 (RTIL) [P][NTf] 混合，以获得适用于电沉积过程的非水支撑电解质。首先在 RTIL 中阳极溶解 Pb(II) 产生的 Pb(II) 标准溶液以及与 0.5 M RTIL 混合并加入已知量 Pb(II) 的橄榄油样品中测试分析策略的可行性和性能。通过应用 D-最优设计优化电化学参数，该设计可优化沉积和再氧化步骤、定量回收和测量时间的效率。最后，该分析程序应用于测定一些意大利特级初榨橄榄油中的 Pb 含量，无需进行矿物化预处理。与微波消解后通过 ICP-QMS 分析获得的数据相比，所提出的方法获得的数据令人满意，两种方法之间的差异在 10%以内，其优点是将预处理时间缩短一半，在室温下操作并避免使用腐蚀性溶剂。
