Synthesis of 1,5-diphenylcarbazide-immobilized alginate/pectin films for colorimetric detection of Cr(VI)

An optical sensor for colorimetric detection of Cr(VI) was synthesized by immobilizing 1,5-diphenylcarbazide (DPC) into alginate/pectin films. The effectiveness of DPC immobilization was increased through the addition of cation surfactant (CTAB) to form hydrophobic-ion pairs. At optimum condition, the films have good selectivity for Cr(VI) compare to other interference metals. The formation of violet color in the films showed its potential application for visual colorimetric detection of Cr(VI). Furthermore, the films developed were shown to be a simple, fast, and sensitive sensors for the direct determination of Cr(VI) with a detection limit as low as 0.233 mg L-2 and response time of 8 minutes.