UV–vis spectrophotometer and smartphone RGB dual mode detection of inorganic arsenic based on hydride generation iodine–starch system

•Hydride generation was utilized as a gaseous sampling technique for the iodine–starch colorimetric analytical system with interferences eliminated.•UV–vis spectrophotometer and smartphone RGB dual mode analytical system was established for the detection of As(III).•Smartphone was used as a portable analytical device for RGB readout.•The proposed method was successful applied to three certified reference water samples and three water samples, with good recoveries of 94%–108%.