Department of Chemistry, Faculty of Science, King Mongkut's University of Technology Thonburi, Prachautid Road, Thungkru, Bangkok, 10140, Thailand.
Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
Analyst. 2021 May 7;146(9):2919-2927. doi: 10.1039/d1an00032b. Epub 2021 Mar 17.
A rapid and highly sensitive paper-based colorimetric device for the on-site detection of ammonia (NH) gas is presented in this study. The detection principle of this device is based upon a change of color from red to yellow on a paper that has been immobilized with a pH indicator, i.e., methyl orange (pK = 3.4), in the presence of NH gas. The color signal of the device can be measured through the hue channel of an HSL system via the application of a smartphone. This device can detect the amount of NH gas within 3 min. The linear relationship between the NH gas concentration and the hue signal was found to be in the range from 6.0 to 54.0 ppbv with R = 0.9971, and the limit of detection was found to be 2.0 ppbv. In addition, this device showed remarkably high selectivity to NH gas amongst the other common volatile organic compounds and general gases that are present in environmental air without the assistance of any membrane material. Furthermore, we demonstrated the applicability of this device for the detection of total NH gas at a chicken farm and in a laboratory, with relative standard deviations of 6.2% and 5.4%, respectively. The developed NH gas device in the study is easy to operate and cost-effective, with the reduction of a large consumption of chemical reagents; also, its signals can be measured simply and then recorded through a smartphone. It is suitable for the application of routine on-site detection of NH gas, especially concerning regions which have limited resources.
本研究提出了一种用于现场检测氨（NH）气体的快速灵敏的纸质比色设备。该设备的检测原理基于在 pH 指示剂甲基橙（pK = 3.4）固定在纸上的情况下，当存在 NH 气体时，颜色从红色变为黄色。可以通过智能手机应用程序通过 HSL 系统的色调通道测量设备的颜色信号。该设备可以在 3 分钟内检测到 NH 气体的量。NH 气体浓度与色调信号之间的线性关系在 6.0 至 54.0 ppbv 范围内，R = 0.9971，检测限为 2.0 ppbv。此外，该设备在没有任何膜材料辅助的情况下，对环境空气中存在的其他常见挥发性有机化合物和一般气体表现出对 NH 气体的显著高选择性。此外，我们展示了该设备在鸡场和实验室检测总 NH 气体的适用性，相对标准偏差分别为 6.2%和 5.4%。本研究中开发的 NH 气体设备易于操作且具有成本效益，减少了大量化学试剂的消耗；此外，其信号可以通过智能手机简单测量并记录。它适用于 NH 气体的常规现场检测应用，特别是在资源有限的地区。
