A Visual Color Response Test Paper for the Detection of Hydrogen Sulfide Gas in the Air.

Hydrogen sulfide (HS) is widely found in oil and natural gas wells and industrial wastewater tanks. Owing to its high toxicity, the monitoring and detection of HS in the air is essential. However, recent techniques for the quantitative detection of HS gas suffer from limitations such as high cost, complicated operation, and insufficient sensitivity, preventing their practical application in industry. Thus, we have developed a portable test paper for real-time and inexpensive monitoring of HS gas by color changes. The test paper had a significantly low HS detection limit of 200 ppb, which is considered safe for humans. Moreover, the color of the test paper did not change noticeably when exposed to CO, N, O, and air environments, indicating that the test paper is selective for HS gas and can be stored for a long time. In addition, we fitted a color difference linear model between the color difference values (Δ) and the concentrations of HS gas. The establishment of the linear model substantiates that the test paper can provide accurate intensity information when detecting HS gas leakage.