Facile detection of hydrogen sulfide through digital image using photo-generated citrate-capped silver nanoprisms

This study presents a digital image colorimetric method for hydrogen sulfide (H₂S) detection using citrate-capped silver nanoprisms (AgNPrs) synthesized via a photo-mediated process. Upon exposure to H₂S, the AgNPrs sensor exhibited a distinct color change from orange to gray, consistent with sulfidation and Ag₂S formation. Key analytical parameters were optimized, including buffer pH (9.0), reaction time (10 min), and sensor volume (60 μL). The method showed two linear response ranges with limits of detection and quantification of 1.87 and 6.24 ppmv, respectively, which are relevant to occupational safety and onsite screening applications. Accuracy and precision were assessed using spike recovery experiments in natural water samples, intra-day and inter-day precision studies, and comparison with a commercial lead acetate paper. The proposed system offers a portable and cost-effective approach for onsite sulfide detection, emphasizing procedural simplicity through additive-free synthesis and smartphone-based analysis.