Highly Thiocyanate-Selective Membrane Electrode Based on the Bis(Benzoylacetone) propylenediimine Copper(II)Complex

A potentiometric thiocyanate-selective sensor based on copper(II) bis(benzoylacetone)propylenediimine complex as a new neutral carrier for a thiocyanate-selective electrode is reported. The response mechanism is discussed in view of the UV spectroscopy technique. The sensor displays a near Nernestian slope of -57.4 ± 0.5 mV per decade. The working concentration range of the electrode is 8.0×10^-7-1.0×10^-1 M with a detection limit of 7.4×10^-7 M. The response time of the sensor in the all concentration ranges is very short (5-10 s). The response of the sensor is independent of pH, in the pH range of 1.7–11.5. The best performance was obtained with a membrane composition of 32.69 % PVC, 57.34 % dibutyl phthalate, 6.82 % complex and 3.15 % methyltrioctylammonium chloride (MTOAC) as additive. The proposed electrode is more selective than other proposed methods for determination of thiocyanate ion over a wide variety of common inorganic and organic anions and it was successfully applied to direct determination of thiocyanate in the presence of other anions in biological, water and waste water samples.