Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada.
Department of Mechanical Engineering, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
ACS Appl Mater Interfaces. 2017 Jun 21;9(24):20748-20761. doi: 10.1021/acsami.7b03968. Epub 2017 Jun 7.
Colorimetric methods are commonly used to quantify free chlorine in drinking water. However, these methods are not suitable for reagent-free, continuous, and autonomous applications. Here, we demonstrate how functionalization of a pencil-drawn film with phenyl-capped aniline tetramer (PCAT) can be used for quantitative electric readout of free chlorine concentrations. The functionalized film can be implemented in a simple fluidic device for continuous sensing of aqueous free chlorine concentrations. The sensor is selective to free chlorine and can undergo a reagent-free reset for further measurements. Our sensor is superior to electrochemical methods in that it does not require a reference electrode. It is capable of quantification of free chlorine in the range of 0.1-12 ppm with higher precision than colorimetric (absorptivity) methods. The interactions of PCAT with the pencil-drawn film upon exposure to hypochlorite were characterized spectroscopically. A previously reported detection mechanism relied on the measurement of a baseline shift to quantify free chlorine concentrations. The new method demonstrated here measures initial spike size upon exposure to free chlorine. It relies on a fast charge built up on the sensor film due to intermittent PCAT salt formation. It has the advantage of being significantly faster than the measurement of baseline shift, but it cannot be used to detect gradual changes in free chlorine concentration without the use of frequent reset pulses. The stability of PCAT was examined in the presence of free chlorine as a function of pH. While most ions commonly present in drinking water do not interfere with the free chlorine detection, other oxidants may contribute to the signal. Our sensor is easy to fabricate and robust, operates reagent-free, and has very low power requirements and is thus suitable for remote deployment.
比色法常用于测定饮用水中的游离氯。然而，这些方法不适用于无试剂、连续和自主应用。在这里，我们展示了如何通过苯封端的苯胺四聚体（PCAT）对铅笔绘制的薄膜进行功能化，从而对游离氯浓度进行定量电读取。功能化薄膜可用于简单的流体装置，连续感测水溶液中的游离氯浓度。该传感器对游离氯具有选择性，并且可以进行无试剂重置以进行进一步测量。与电化学方法相比，我们的传感器具有优势，因为它不需要参比电极。它能够定量检测 0.1-12ppm 范围内的游离氯，其精度高于比色法（吸光度）。PCAT 与暴露于次氯酸盐的铅笔绘制薄膜之间的相互作用通过光谱学进行了表征。先前报道的检测机制依赖于测量基线偏移来定量游离氯浓度。这里演示的新方法测量暴露于游离氯时的初始尖峰大小。它依赖于由于间歇性 PCAT 盐形成而在传感器薄膜上快速建立的电荷。它的优点是比测量基线偏移快得多，但如果不使用频繁的重置脉冲，则无法用于检测游离氯浓度的逐渐变化。研究了 PCAT 在游离氯存在下的稳定性，作为 pH 的函数。虽然饮用水中常见的大多数离子不会干扰游离氯的检测，但其他氧化剂可能会导致信号干扰。我们的传感器易于制造且坚固耐用，无需试剂，功率要求非常低，因此适合远程部署。
