Chromium(III) ion selective electrode based on oxalic acid bis(cyclohexylidene hydrazide)

A poly(vinyl chloride) membrane sensor based on oxalic acid bis (cyclohexylidene hydrazide) as membrane carrier was prepared and investigated as a Cr(III)-selective electrode. The electrode reveals a Nernstian behavior (slope 19.8 +/- 0.4 mV decade(-1)) over a wide Cr(III) ion concentration range 1.0 X 10(-7) -1.0 X 10(-2) mol dm(-3) with a very low limit of detection (i.e., down to 6.3 x 10(-8) mol dm(-3)). The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 1.7-6.5. The electrode possesses advantage of very fast response, relatively long lifetime and especially good selectivity to wide variety of other cations. The sensor was used as an indicator electrode, in the potentiometric titration of chromium ion and in the determination of Cr(III) in waste water and alloy samples.