Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Thailand.
Office of Police Forensic Science, Royal Thai Police, Bangkok, 10330 Thailand.
Analyst. 2021 Mar 8;146(5):1579-1589. doi: 10.1039/d0an02455d.
This work presents the first planar three-electrode electrochemical sensor comprising local gold leaf as the working electrode and printed, or hand-drawn, counter and reference electrodes, respectively. The gold leaf was mounted on a polyvinyl chloride (PVC) adhesive sheet (15 mm × 30 mm) and covered with a second PVC sheet printed with the counter and reference electrodes. This sheet has a 3 mm circle and a 2 mm × 3 mm rectangle removed to expose the gold electrode area and electrical contacts, respectively. A third shorter insulating layer with a 10 mm circular hole was placed on top to delineate the sensing area of all electrodes. The sensor displayed expected performances in various modes of operation, such as cyclic voltammetry, square wave voltammetry and anodic stripping voltammetry. For the latter mode, the limit of detection of Pb(ii) was 3.2 μg L-1, compliant with regulation for drinking water (10 μg L-1 Pb(ii)). Although designed as a disposable unit, the electrode is effective for up to 200 cycles and applicable for multiple use. The gold leaf was modified by electrodeposition of the gold network and large nano-size gold particles which significantly enhanced the sensitivity of all voltametric sensing, giving lower limits of detection. For stripping voltammetry, the electroplating structure modification improved the simultaneous detection of lead and copper, with the copper response increasing 6-fold. The device has the capability of on-site identification of copper/lead bullets from gunshot residues within 6 min.
本工作提出了第一个平面三电极电化学传感器，包含局部金叶作为工作电极，以及分别印刷或手工绘制的对电极和参比电极。金叶被安装在聚氯乙烯（PVC）胶带上（15mm×30mm），并用印有对电极和参比电极的第二张 PVC 覆盖。该薄片有一个 3mm 的圆和一个 2mm×3mm 的矩形被切除，分别露出金电极区域和电接触点。第三层较短的绝缘层，带有 10mm 的圆形孔，被放置在顶部，以描绘所有电极的感测区域。该传感器在各种操作模式下，如循环伏安法、方波伏安法和阳极溶出伏安法中，显示出预期的性能。对于后一种模式，Pb（ii）的检测限为 3.2μg L-1，符合饮用水规定（10μg L-1 Pb（ii））。虽然设计为一次性使用单元，但该电极可有效使用多达 200 次，并且可多次使用。金叶通过金网络和大纳米尺寸金颗粒的电沉积进行修饰，这显著提高了所有伏安传感的灵敏度，给出了更低的检测限。对于溶出伏安法，电镀结构修饰提高了铅和铜的同时检测能力，铜的响应增加了 6 倍。该设备具有在 6 分钟内从枪击残留物中现场识别铜/铅弹的能力。
