A simple and sensitive colorimetric sensor for cadmium (II) detection based on self-assembled trimethyl tetradecyl ammonium bromide and murexide on colloidal silica

Abstract A sensitive and selective colorimetric sensor based on self-assembled trimethyl tetradecyl ammonium bromide (TTAB) and murexide on colloidal silica surface was developed for the detection of cadmium ion (Cd2+). Cd2+ was formed complex with murexide on the colorimetric probe (TTAB/Murexide/Silica sol) which the solution was changed immediately from light purple to orange color and was detected by spectrophotometry at 485 nm. Under the optimum conditions, the linearity was in the range of 0.01-0.12 mM with the determination coefficient of 0.9933, the limit of detection was 0.21 µM. Good precision was obtained with %RSD less than 1.28 and 4.17 for the intra-day and inter-day, respectively. The proposed colorimetric method, TTAB/Murexide/Silica sol, was successfully applied for determination of Cd2+ in rice samples and the obtained results were comparable to those from AAS method. In addition, smartphone combined with Image J program was also employed for the determination of Cd2+. The superiority of this colorimetric sensor is simple, rapid and low cost.