LAUSR

Abstract Herein, we developed a smartphone-based portable absorbance device with the wavelength covered from the ultraviolet (365 nm) to near infrared (780 nm) regions, expanding the applications of visualized colorimetric analysis. In a three-channel cuvette, the absorbance cell was sandwiched between two fluorescence detection chambers. The intensities of incident light and transmitted light with respect to the absorbance cell were measured from the fluorescence intensity of the reference and measurement chambers, respectively. The as-measured absorbance obeys the Lambert-Beer law in the range of 0 ~ 1.0. By using red-emitting carbon quantum dots as the detection fluorophore, the determinations of folic acid by ultraviolet absorbance (at 365 nm), dissolved oxygen by visible absorbance (at 505 nm), and hypochlorous acid by near-infrared absorbance (at 780 nm) were demonstrated. The influence of the variation in the light source intensity on the absorbance was corrected by the ratiometric strategy. The portable absorbance device was applied for the field analysis of dissolved oxygen in environmental water samples, offering the advantages of portability, reliability and accuracy for field analysis.