Development of Chromium(III)-selective Potentiometric Sensor by Using Synthesized Pyrazole Derivative as an Ionophore in PVC Matrix and its Applications

A novel poly(vinyl chloride) membrane potentiometric sensor for chromium(III) ions based on the use of 5,5 '-(1,4-phenylene)bis(3-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide) as a neutral ionophore was developed. The optimum composition of the best performing membrane contained ionophore, potassium tetrakis (p-chlorophenyl) borate (KTpClPB), dibutyl phthalate (DBP), and poly(vinyl chloride) (PVC) in the ratio of 5.5:1.5:55:38 (mg). The sensor exhibits a working concentration range of 1.0 x 10(-5)-1.0 x 10(-1) mol L-1 and a detection limit of 1.7 x 10(-6) mol L-1. The sensor shows good selectivity for chromium(III) ions over a number of cations including alkali, alkaline earth, heavy and transition metals. The response time of the sensor is 8 s. In addition, the developed sensor shows good reusability and stability. The sensor operates in the wide pH range of 5.0-11.0. The sensor could be used as an indicator electrode in the quantification of Cr3+ ions by potentiometric titration against ethylenediaminetetraacetic acid (EDTA). Finally, this sensor was successfully used for the determination of chromium(III) in commercial water, purification water and wastewater.