High-Sensitive and Selective Liquid Membrane Electrode for Direct Determination of Trace Amounts of Chromium

N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide was used as a selective sensing material in the PVC membrane to construction of a new chromium ion selective electrode. This liquid membrane electrode worked well with a Nernstian response of 19.7 ±0.4 mV decade-1 of Cr(III) in a wide dynamic concentration range of 8.0× 10-6-1.0×10-1 M. The electrode had relatively short response time (about 5 s), and it was found to produce stable responses for more than 60 days. The effects of some factors such as internal solution, pH, life time and selectivity were investigated. The electrode has a useful working pH range of 3.5–8. Selectivity coefficients determined with match potential method. The selectivity coefficients indicate high selectivity towards Cr(III) ions. The practical utility of the Cr(III) ion sensor has been demonstrated by using it as an indicator electrode in potentiometric titration of Cr(III) with EDTA and for direct determination of Cr(III) in tea and Cocoa powder samples.