Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
Anal Chem. 2010 Mar 1;82(5):1727-32. doi: 10.1021/ac9022555.
A novel lab-on-paper device combining electrochemical and colorimetric detection for the rapid screening of Au(III) in the presence of a common interference, Fe(III), in industrial waste solutions is presented here. With dilute aqua regia (0.1 M HCl + 0.05 M HNO(3)) as the supporting electrolyte, square wave voltammetry on paper provided a well-defined reduction peak for Au(III) at approximately 287 +/- 12 mV vs Ag/AgCl. Under the optimized working conditions, the calibration curve showed good linearity in the concentration range of 1-200 ppm of Au(III) with a correlation coefficient of 0.997. The limit of detection (LOD) of the proposed method is 1 ppm. Interferences from various cations were also studied. Fe(III) is the only metal that affects the electrochemical determination of Au(III) when present above a 2.5-fold excess concentration of that of the Au(III). To overcome this limitation, a colorimetric method was used to simultaneously detect Fe(III) as a screening tool. The procedure was then successfully applied to determine Au(III) in gold-refining waste solutions. The results are in agreement with those obtained from inductively coupled plasma-atomic emission spectrometry (ICP-AES).
本文提出了一种新颖的纸上实验室装置，将电化学和比色检测结合起来，用于快速筛选工业废水中存在的 Au(III)，同时存在常见干扰物质 Fe(III)。在稀王水（0.1 M HCl + 0.05 M HNO(3)）作为支持电解质的情况下，纸基上的方波伏安法在约 287 +/- 12 mV vs Ag/AgCl 处提供了 Au(III)的明确还原峰。在优化的工作条件下，校准曲线在 1-200 ppm 的 Au(III)浓度范围内表现出良好的线性关系，相关系数为 0.997。该方法的检出限（LOD）为 1 ppm。还研究了各种阳离子的干扰。当 Fe(III)的浓度超过 Au(III)的 2.5 倍时，是唯一会影响 Au(III)电化学测定的金属。为了克服这一限制，使用比色法作为筛选工具同时检测 Fe(III)。然后成功地将该方法应用于金精炼废水中 Au(III)的测定。结果与电感耦合等离子体原子发射光谱法（ICP-AES）的结果一致。
