Selective lead ion sensing via cotton pad-based NaEDTA capped AuNPs: A smartphone-assisted colorimetric method.

Herein, NaEDTA-capped AuNPs specifically designed for selective smartphone-assisted colorimetric detection are synthesized and characterized. NaEDTA-capped AuNPs was synthesized and characterized by UV-Visible spectroscopy, ATR, Raman, XRD, SEM and EDX. The calculated activation energy of the produced nanoparticles was 0.2 eV. Using XRD and SEM, the average crystallite size was found to be approximately 25 nm. Only Pb and Cd, among the following metal ions: Mg, K, Ca, Co, Ni, Ba, Hg, Bi, Pb, and Cd, caused the AuNaEDTA solution's hue to shift from reddish in color to blue. Pb and Cd were distinguished using a NaS solution. Cotton pad with AuNaEDTA integrated served as the substrate for metal ion adsorption. The GIMP software-supported smartphone was used to implement the color contrast (R) method. In the 10-2000 μM range, a straight line represented the relationship between 1/R and Pb ion concentrations, with a limit of detection (LOD) of 0.28 μM was revealed. Real water sample collected from Rupsa River, Khulna, Bangladesh was tested by the developed colorimetric method to be 80 μM of Pb ion. Combining the prevalence of smartphones and the potential of nanotechnology, a cotton-pad based platform functionalized with AuNaEDTA may be a ground-breaking method for the detection of Pb ions in various media.