A portable/miniaturized analytical kit for on-site analysis: Chemical vapor generation-visual colorimetric and smartphone RGB dual-mode for detection of sulfide ion in water and food additives

Chemical vapor generation (CVG) was used as a gaseous sample introduction technique for the visual/smartphone RGB readout colorimetric system, with the advantages of efficient matrix elimination and high vapor generation efficiency, this analytical system exhibits a good selectivity and sensitivity. Sulfide ion (S2-) in solution was transformed to its volatile form (H2S), the generated H2S reacted with a silver -containing metal organic framework (Ag-BTC) selectively, Ag2S was thus generated. Ag-BTC (fabricated on paper sheet) changed from white to dark brown, the color variance was identified by smartphone and naked -eye simultaneously. Under the optimized conditions, a limit of detection of 0.02 mu g/mL was obtained by naked -eye. Several water samples and commercial food additives were analyzed for confirming its accuracy and potential application for on -site detection, recoveries ranging 94-110 % were obtained. To meet the demand of on -site analysis of S2 -, this colorimetric system was integrated in a portable/miniaturized analytical kit. It is an easy -used, affordable and portable analytical kit for S2- detection in field.