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Comparison between Modified and Unmodified Carbon Paste Electrodes for Hexavalent Chromium Determination
Electroanalysis ( IF 2.7 ) Pub Date : 2018-09-21 , DOI: 10.1002/elan.201800505
Nazha Hilali 1 , Abdelghani Ghanam 1 , Hasna Mohammadi 1 , Aziz Amine 1 , Juan José García-Guzmán 2 , Laura Cubillana-Aguilera 2 , José María Palacios-Santander 2
Affiliation  

This work consists of developing a simple electroanalytical method which allows the speciation of Cr(VI). Gold modified Carbon Paste Electrodes (CPEs) and unmodified CPEs have been tested for the determination of Cr(VI) in presence of an excess of Cr(III) by using differential pulse voltammetry (DPV), without any accumulation or pre‐concentration time. Several parameters affecting the analytical performances of the designed electrodes were investigated, including: electrodeposition technique of AuNPs onto the CPE, amount of AuNPs dropped on the electrode surface, supporting electrolyte, presence of Cr(III), presence of chloride ions and concentration of diphenylcarbazide (DPC). Under the optimal conditions, the use of unmodified CPE in an acidic medium containing DPC exhibited a high selectivity and a good detection limit of 19 μg ⋅ L−1, which is much lower than the admissible concentration fixed by the World Health Organization (50 μg ⋅ L−1). A linear range from 50 to 260 μg ⋅ L−1 was obtained with a relative standard deviation of 7.75 %. Furthermore, as opposed to the AuNPs‐modified CPE, the current response of Cr(VI) obtained at the unmodified CPE was not affected by the presence of chloride ions and trivalent chromium. Finally, the proposed method was successfully applied for the determination of Cr(VI) in real tap water samples with satisfactory results.

中文翻译:

六价铬测定中修饰和未修饰碳糊电极的比较

这项工作包括开发一种简单的电分析方法,该方法可以形成Cr(VI)。已使用微分脉冲伏安法(DPV)对存在过量Cr(III)的金修饰碳糊电极(CPE)和未修饰CPE进行了测定Cr(VI)的测试,没有任何累积或预浓缩时间。研究了影响设计电极分析性能的几个参数,包括:AuNPs在CPE上的电沉积技术,AuNPs滴在电极表面上的量,支持电解质,Cr(III)的存在,氯离子的存在和二苯基卡巴肼的浓度(DPC)。在最佳条件下,在含DPC的酸性介质中使用未改性的CPE表现出高选择性和19μg⋅L的良好检出限-1,远低于世界卫生组织规定的容许浓度(50μg⋅L -1)。获得50至260μg·L -1的线性范围,相对标准偏差为7.75%。此外,与AuNPs改性的CPE相对,未改性的CPE上获得的Cr(VI)的电流响应不受氯离子和三价铬的存在的影响。最终,该方法成功用于实际自来水样品中Cr(VI)的测定,结果令人满意。
更新日期:2018-09-21
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