The sensitivity of the paper-based colorimetric sensors containing the modified AgNPls for Cu2+ detection is related to various
factors including, pH of buffer solutions, concentrations of AgNPls and S2O32 and incubation time. Therefore, these parameters were
optimized by using 100 ng mL1 of Cu2+. The difference in the color
intensity values of the AgNPls before and after the addition of Cu2+
(DI = Isample Iblank) was determined.