Chromium measurement in pharmaceutical samples: a comparative study of three new membrane electrodes with different electron-ion exchangers

The present study deals with synthesis of N -(thiazol-2-ylcarbamothioyl) benzamide. It was utilized as a neutral ionophore for designing three types of chromium( iii ) sensors including coated wire ion selective electrodes (CW-ISEs), ion selective electrodes with liquid internal electrolyte (LIE-ISEs), and solid-state ion selective electrodes (SS-ISEs). UV-visible spectrophotometry was used to confirm the affinity of N -(thiazol-2-ylcarbamothioyl) benzamide to chromium( iii ). It was found that a membrane with a composition of 2% NaTPB, 8% ionophore, 60% DBP, and 30% PVC showed the best performance and a Nernstian slope of 21.6 mV per decade. Scanning electron microscopy was used to assess the PVC membrane morphology. The existence of chromium( iii ) in the liquid membrane matrix was proved by energy-dispersive X-ray spectroscopy. Detection limits for SS-ISE (1 × 10 −6 M) and CW-ISE (1 × 10 −6 M) were enhanced relative to LIE-ISE (1 × 10 −5 M). All three electrodes showed a response time of about 5 s. The sensors' applicable pH range was 4.0-6.0. Fourier transform infrared spectra recorded through the electrode membrane showed that chromium( iii ) ion can interact with sulfur, nitrogen and oxygen atoms of N -(thiazol-2-ylcarbamothioyl) benzamide. The sensors were utilized as indicator electrodes in chromium( iii ) potentiometric titration with ethylenediaminetetraacetic acid and for directly measuring chromium( iii ) in some pharmaceutical samples. Three types of chromium( iii ) sensors with different electron-ion exchangers were fabricated using the newly synthesized ionophore. The sensors were successfully applied for potentiometric measurement of chromium( iii ) in pharmaceutical samples.