Abstract
A selective and inexpensive chemical paper-based sensor for the detection of gaseous H2S is presented. The triggering of the sensing mechanism is based on an arene-derivative dye which undergoes specific reactions in the presence of H2S, allowing for colorimetric analysis. The dye is embedded into a porous cellulose matrix. We passively exposed the paper strips to H2S generated in situ, while the absorbance was monitored via an optic fiber connected to a spectrophotometer. The kinetics of the emerging absorbance at 534 nm constitute the sensor response and maintain a very stable calibration signal in both concentration and time dimensions for quantitative applications. The time and concentration dependence of the calibration function allows the extraction of unusual analytical information that expands the potential comparability with other sensors in the literature, as the limit of detection admissible within a given exposure time. The use of this specific reaction ensures a very high selectivity against saturated vapors of primary interferents and typical volatile compounds, including alkanethiols. The specific performance of the proposed sensor was explicitly compared with other colorimetric alternatives, including standard lead acetate strips. Additionally, the use of a smartphone camera to follow the color change in the sensing reaction was also tested. With this straightforward method, also affordable for miniature photodiode devices, a limit of detection below the ppm scale was reached in both colorimetric approaches.
Highlights
IntroductionH2 S is a toxic, water-soluble, and flammable gas produced as a byproduct of a wide variety of industrial processes (petroleum and gas natural industries, coal mines, or paper, fertilizer and detergent production) or by the anoxygenic metabolism of some types of bacteria [1]
H2 S is a toxic, water-soluble, and flammable gas produced as a byproduct of a wide variety of industrial processes or by the anoxygenic metabolism of some types of bacteria [1]
The spectral shapes of these bands are close to those reported by Montoya et al [85], while the maxima of the absorption peaks at 543 nm for (NBD)SH and 406 nm for (NBD)2 S are slightly different from these prior results due to hydrogen bonding and polarity differences provoked by solvent effects
Summary
H2 S is a toxic, water-soluble, and flammable gas produced as a byproduct of a wide variety of industrial processes (petroleum and gas natural industries, coal mines, or paper, fertilizer and detergent production) or by the anoxygenic metabolism of some types of bacteria [1]. It is lethal at relatively low concentration levels [2] because it is absorbed by the lungs quickly, causing blood poisoning, headache and nausea, among other symptoms [3]. There is a constant requirement to develop portable and real-time quantitative methods for low levels of H2 S in gas streams or the atmosphere
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