Department of Civil and Environmental Engineering, University of Massachusetts Lowell, Lowell, MA, USA.
Department of Civil and Environmental Engineering, University of Massachusetts Lowell, Lowell, MA, USA.
Anal Chim Acta. 2020 Apr 22;1107:63-73. doi: 10.1016/j.aca.2020.02.015. Epub 2020 Feb 7.
One of the challenges preventing rapid, onsite voltammetric detection of arsenic(III) is the overlapping oxidation peak of copper(II). This paper describes a novel methodology for the voltammetric detection of trace levels of arsenic(III) in the presence of high copper(II) concentrations (up to the action level of 1.3 mg L set by the US EPA for drinking water). Square wave stripping voltammetry tests were performed using disposable carbon screen printed electrodes modified with gold nanostars on samples buffered with Britton-Robinson buffer. The optimized parameters for accurate codetection of arsenic(III) and copper(II) were a buffer pH of 9.5, a loading of gold nanostars of 2.39*10 nmol per electrode, a deposition voltage of -0.8 V, and a deposition time of 180 s. Based on calibration testing, the limits of detection for arsenic(III) and copper(II) were determined to be 2.9 μg L and 42.5 μg L, respectively. Furthermore, the linear ranges for arsenic and copper were 0-100 μg L and 0-250 μg L with sensitivities of 0.101 μA (μg L) and 0.121 μA (μg L), respectively. Interference testing was performed with several common ionic species, sodium bicarbonate, sodium chloride, tannic acid, iron(iii) chloride, magnesium chloride, calcium nitrate, and sodium sulfate, with only sodium bicarbonate significantly affecting the response. Validation testing in real-world samples was performed by comparison with graphite furnace atomic absorption spectroscopy. The validation testing demonstrated good accuracy and precision, expressed as percent recovery and relative standard deviation (RSD), respectively, in river water and tap water, with mean percent recoveries of 87.7% (RSD = 4.20%) and 83.2% (RSD = 10.02%), respectively.
一种阻碍快速现场电化学检测砷(III)的挑战是铜(II)的氧化峰重叠。本文描述了一种新的方法，用于在高浓度铜(II)（高达美国环保署为饮用水设定的 1.3mg/L 行动水平）存在下电化学检测痕量砷(III)。在使用 Britton-Robinson 缓冲液缓冲的样品中，使用金纳米星修饰的一次性碳丝网印刷电极进行方波溶出伏安法测试。准确检测砷(III)和铜(II)的优化参数为缓冲液 pH 值为 9.5、每个电极负载 2.39*10 nmol 的金纳米星、沉积电压为-0.8V 和沉积时间为 180s。基于校准测试，砷(III)和铜(II)的检测限分别确定为 2.9μg/L 和 42.5μg/L。此外，砷和铜的线性范围分别为 0-100μg/L 和 0-250μg/L，灵敏度分别为 0.101μA（μg/L）和 0.121μA（μg/L）。用几种常见的离子种类、碳酸氢钠、氯化钠、单宁酸、三氯化铁、氯化镁、硝酸钙和硫酸钠进行了干扰测试，只有碳酸氢钠对响应有显著影响。通过与石墨炉原子吸收光谱法进行比较，对实际样品进行了验证测试。在河水和自来水中的验证测试表明，具有良好的准确性和精密度，分别表示为回收率和相对标准偏差（RSD），回收率平均值分别为 87.7%（RSD=4.20%）和 83.2%（RSD=10.02%）。
