In this work, a new strategy has been reported for the portable detection of H2S based on Fe-doped hydroxyapatite nanoparticles (Fe-HA) using a colorimetric paper test strip integrated with a smartphone platform. Fe-HA NPs were fabricated successfully via recycling waste coal ash. The obtained probe response toward H2S was through a distinct visual color change. The sensing mechanism is based on the displacement reaction, in which PO43‑ is replaced by S2‑. The prepared test strip shows high selectivity, and the other compounds containing thiol and sulfur anion have a negligible effect on the detection of H2S. The designed scheme is applied for H2S detection in the concentration range of 0.5−130 ppm with a limit of detection of 70 ppb. Furthermore, such a disposable sensor was used as a practical system for monitoring H2S in actual water samples, suggesting the promising potential of this platform for suitable analysis of H2S in an aqueous environment.
