DETERMINATION OF THE ANTIOXIDANT IRGANOX-1076 BY ANODIC VOLTAMMETRY AND FLOW-INJECTION WITH PULSED AMPEROMETRIC DETECTION AT A GLASSY-CARBON ELECTRODE

An electroanalytical study of the Irganox 1076 oxidation process at a glassy carbon electrode in an aqueous 60% ethanolic medium using different voltammetric techniques has been carried out. The results obtained by differential pulse voltammetry allowed the development of a method for the determination of this antioxidant using a calibration graph in the 1.0 x 10(-6)-2.5 x 10(-5) mol l(-1) Irganox 1076 concentration range (r = 0.9998). The coefficient of variation was 3.3% for a concentration level of 1.0 x 10(-5) mol l(-1), with a limit of determination of 7.7 x 10(-7) mol l(-1) and a limit of detection of 2.3 x 10(-7) mol l(-1). The effect of other antioxidants and plasticizers has been studied. Good results were obtained by applying the proposed differential pulse voltammetric method to the determination of Irganox 1076 in commercial poly(vinyl chloride) based plastics. A flow-injection method with pulsed amperometric detection based on such an oxidation process is also described. The pulse waveform was optimized in order to ascertain the cleaning of the electrode surface and also to obtain the best sensitivity. Calibration graphs were linear within the ranges 2.0 x 10(-7)-10.0 x 10(-7) mol l(-1) (r = 0.998) and 1.0 x 10(-6)-10.0 x 10(-6) mol l(-1) (r = 0.999). The coefficient of variation was 2.3% and the limits of detection and determination were 8.0 x 10(-8) mol l(-1) and 2.7 x 10(-7) mol l(-1), respectively.