Novel Potentiometric Sensors for the Determination of Cochineal Red A and its Application to Food Analysis

In this research the novel potentiometric sensors have been evaluated for theselective determination of cochineal red a (cra) in colored food. pvc membrane(pme) and coated graphite electrode (cge) have been prepared based ontetraphenylphosponium-cra ion pair as the electro active substance. the electrodesreveal linear emf-pcra responses over wide concentration ranges of (1.0×10-4-1.0×10-1m with a slope -19.0 mv decade-1 for pme) and (1.0×10-6-1.0×10-1 m with a slope-20.2 mv decade-1 for cge) and limits of detection of 7.8×10-5 for pme and 8.0×10-7for cge. the potentiometric responses were independent of the ph of the test solutionin the ph range 4-7. the proposed electrodes showed very good selectivity over a widevariety interfering ions. electrodes have been successfully applied to the determinationof cochineal red a in food products by direct potentiometric method. the results werein good agreement with the value obtained by using the official method (hplcmeasurements).