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首页> 外文期刊>International Journal of Electrochemical Science >Speciation of Cr(VI) and Cr(III) in Water Samples by Adsorptive Stripping Voltammetry in the Presence of Pyrogallol Red Applying a Selective Accumulation Potential
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Speciation of Cr(VI) and Cr(III) in Water Samples by Adsorptive Stripping Voltammetry in the Presence of Pyrogallol Red Applying a Selective Accumulation Potential

机译：在有邻苯三酚红的条件下利用选择性累积电位通过吸附溶出伏安法测定水样中的六价铬和三价铬

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摘要

An adsorptive stripping voltammetric procedure for the speciation of Cr(VI) and Cr(III) in thepresence of pyrogallol red (PGR) is presented. The method is based on the previous reduction ofCr(VI) to Cr(III) at the electrode surface, its complexation with PGR, and the later reduction ofIII II Cr GR to Cr GR at .85 V. The effects of various operational parameters such as pH, ligandconcentration (CPGR), and accumulation potential and time (Eads, tads) were optimized. These studieswere carried out using individual Cr(VI) and Cr(III) solutions and also mixtures of them. The resultsshowed that the proper choice of the adsorptive potential produces selectivity for Cr(VI) in theIII presence of Cr(III). At an Eads of 0.00 V only Cr(VI) produces the reduction signal of Cr GR at.85 V, while at an Eads of .68 V both Cr(VI) and Cr(III) produce this signal. Total chromium wasdetermined after oxidation of Cr(III) to Cr(VI) by UV radiation in the presence of H2O2. Theconcentration of Cr(III) was evaluated as the difference between total chromium and Cr(VI). Under the best experimental conditions (pH 4.5; CPGR 0.25 mol L ; Eads .68 V and tads 60 s), the peak current is proportional to the total Cr concentration up to 20.0 g L , with a 3detection limit of 0.05 g L . The relative standard deviation for a Cr(VI) solution (9.8 g L ) was 1.8 % for six successive assays.The method was validated using synthetic sea water (ASTM D665) spiked with Cr(VI) and Cr(III),and with a certified reference water (NCS ZC76307). In this reference material total chromium wasdetermined as Cr(III) other aliquot of reference sample was oxidized and the total chromiumdetermined as Cr(VI).
机译：提出了一种在邻苯三酚红（PGR）存在下Cr（VI）和Cr（III）的形态吸附溶出伏安法。该方法基于先前在电极表面将Cr（VI）还原为Cr（III），与PGR络合以及随后在0.85 V下将III II Cr GR还原为Cr GR的方法。在pH值，配体浓度（CPGR）以及积累潜力和时间（Eads，tads）方面进行了优化。这些研究是使用单独的Cr（VI）和Cr（III）溶液以及它们的混合物进行的。结果表明，在Cr（III）III的存在下，正确选择吸附势会产生对Cr（VI）的选择性。在0.00 V的Eads时，只有Cr（VI）产生85 V时Cr GR的还原信号，而在0.68 V的Eads时，Cr（VI）和Cr（III）都产生该信号。在H2O2存在下，通过UV辐射将Cr（III）氧化为Cr（VI）后，测定总铬。 Cr（III）的浓度被评估为总铬和Cr（VI）之间的差异。在最佳实验条件下（pH 4.5; CPGR 0.25 mol L; Eads .68 V和tads 60 s），峰值电流与总Cr浓度成正比，直至20.0 g L，3次检测限为0.05 g L。六次连续测定的Cr（VI）溶液（9.8 g L）的相对标准偏差为1.8％。该方法已使用掺有Cr（VI）和Cr（III）的合成海水（ASTM D665）进行了验证。经认证的参考水（NCS ZC76307）。在该参考材料中，将总铬确定为Cr（III），将参考样品的其他等分试样氧化，并将总铬确定为Cr（VI）。

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