Electrochemistry and Optical Spectroscopy Center of Excellence, Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.
Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok, 10110, Thailand.
Mikrochim Acta. 2018 Jun 11;185(7):324. doi: 10.1007/s00604-018-2821-7.
A multistep paper-based analytical device (mPAD) was designed and applied to the voltammetric determination of total inorganic arsenic. The electrodeposition of gold nanoparticles on a boron-doped diamond (AuNP/BDD) electrode and the determination of total inorganic arsenic is accomplished with a single device. Total inorganic arsenic can be determined by first reducing As(V) to As(III) using thiosulfate in 1.0 mol L HCl. As(III) is then deposited on the electrode surface, and total inorganic arsenic is quantified as As(III) by square-wave anodic stripping voltammetry the potential range between -0.25 V and 0.35 V (vs. Ag/AgCl), best at around 0.05 V. Under optimal conditions, the voltammetric response for As(III) detection is linear in the range from 0.1 to 1.5 μg mL and the limit of detection (3SD/slope) is 20 ng mL. The relative standard deviation at 0.3, 0.7 and 1.0 μg mL of As(III) are 3.6, 4.3 and 3.3, respectively (10 different electrodes). The results show that the assay has high precision, a rather low working potential, and excellent sensor-to-sensor reproducibility. The method was employed to the determination of total inorganic arsenic in rice samples. Results agreed well with those obtained by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Graphical abstract A multistep paper-based analytical device (mPAD) is described that integrates a AuNP/BDD electrode preparation step and a detection step into a single device. The AuNPs are easily deposited on the BDD electrode by applying electrodeposition potential. The total inorganic arsenic concentration in rice samples was determined by using square-wave anodic stripping voltammetry.
一种多步纸基分析装置（mPAD）被设计并应用于总无机砷的伏安法测定。金纳米粒子在掺硼金刚石（AuNP/BDD）电极上的电沉积和总无机砷的测定是在单个装置中完成的。总无机砷可以通过首先在 1.0 mol L HCl 中用硫代硫酸盐将 As(V)还原为 As(III)来测定。然后，As(III)沉积在电极表面，通过方波阳极溶出伏安法在-0.25 V 和 0.35 V（相对于 Ag/AgCl）的电位范围内（最佳约 0.05 V）定量测定总无机砷。在最佳条件下，As(III)检测的伏安响应在 0.1 至 1.5 μg mL 的范围内呈线性，检测限（3SD/斜率）为 20 ng mL。在 0.3、0.7 和 1.0 μg mL 的 As(III)时的相对标准偏差分别为 3.6、4.3 和 3.3（10 个不同电极）。结果表明，该测定法具有高精度、较低的工作电位和出色的传感器间重现性。该方法用于稻米样品中总无机砷的测定。结果与电感耦合等离子体-光学发射光谱法（ICP-OES）的结果吻合良好。
