Chromatic analysis by monitoring unmodified silver nanoparticles reduction on double layer microfluidic paper-based analytical devices for selective and sensitive determination of mercury(II)

Use of a Smartphone as a Colorimetric Analyzer in Paper-based Devices for Sensitive and Selective Determination of Mercury in Water Samples

“…S1d, (2-3), Supporting Information). Only gray intensity in the blue channel (GB) (since the most sensitive response to the change of Hg 2+ ions concentration were observed) 18 on the detection zone of the μPAD were recorded by smartphone camera with the homemade software application installed (called "CAnal") under housing light controlling system made from PVC pipe (f8 cm × 9 cm high) with LED white light (Fig. S3, Supporting Information).…”

“…The calibration curve of three different synthesis batches of unmodified AgNPs generated by an Android smartphone camera with the homemade CAnal installed were compared to a conventional detection system on μPAD (digital camera coupled with ImageJ software operated by computer). 18 For sample analysis of Hg 2+ (Fig. S5, Supporting Information), the sample solutions were applied to the double-layer μPAD coated with the as-prepared unmodified AgNPs, and then the picture was taken by the user.…”

“…The calibration curve (0.01 -10 mg L -1 ) plotted between the log(GB-GB0) value and concentration of Hg 2+ , mg L -1 comparing three syntheses of unmodified AgNPs at different batches generated by digital camera coupled with ImageJ software operated by computer 18 were shown in good agreement when compared to the results obtained by Android smartphone camera (smartphone 1) with the developed homemade CAnal application installed, at a 95% confidence level ( Fig. 2 and Table S6, Supporting Information).…”

“…2,[13][14][15][16][17][18] Recently, the proof of concept for a μPAD for the determination of Hg 2+ in water using chromatic analysis based on a simple red green blue (RGB) color model has been developed by our group. 18 The μPAD was fabricated by alkyl ketene dimer (AKD)-inkjet printing and doped with our synthetic unmodified silver nanoparticles (AgNPs), which progressively vanished away from deep yellow to brighter yellow with increasing Hg 2+ ion concentration in water samples, corresponding to color intensity change. The zone of images was recorded by a digital camera under an optimized control light box and the color intensity signal was further analyzed using ImageJ image processing software through the grayscale (gray intensity) in blue channel (GB).…”

“…Subsequent deposition of elementary Hg onto the surface of AgNPs also occurred, resulting in amalgam particles of mercury (Hg-Ag). 18,19 Our previous prototype provided high sensitivity, a low limit of detection, short analysis time and good selectivity towards Hg 2+ determination against other studied foreign ions in waters. Moreover, the benefits of the μPAD application compared to the same reaction in bulk solution include the advantages of simplicity in color change monitoring (by a camera), small sample volume uptake (2 μL) and minimized interference effects from suppression of charge stabilized unmodified AgNPs due to the fact that unmodified AgNPs are located inside the cellulose matrix instead of dispersed in the bulk aqueous circumstance.…”