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  • 1
    Electronic Resource
    Electronic Resource
    Voltammetric determination of the antioxidant tert-butylhydroxytoluene (BHT) at a carbon paste electrode modified with nickel phthalocyanine (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 475-479 
    Details
    ISSN: 1040-0397
    Keywords: Modified electrode ; Electrocatalysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The voltammetric behaviar of the antioxidant tert-butyltydroxytoluene (BHT) at a carbon paste electrode modified with nickel phthalocyanine is described, and method for the determination of this antioxidant based on its oxidations at the modified electrode it proposed. Cyclic voltammograms showed a well defined oxidations peak for BHT at potentials approximately. 200 mV lower than the poorly defined peck obtained in the absence of the electocatalyst. A 35%, methanol :water medium, a modifier concentrations of 2%, and pH 2 were chosen as working conditions. Results obtained suggest that the oxidation signal arisen as a result of BHT chemically reducing Ni(II)to Ni(I) in the phthalocyanine, and the subsequent electrochemical oxidations of the latter. Using differential pulse voltammetry at ΔE =50 mV, a linear calibration range was obtained between 1 and 50 mg L-1 BHT with a detection limit of 0.17 mg L-1 BHT interferences from other substances commonly present in commercial antioxidant mixtures were tested. The developed method was applied to the determinations of BHT in stabilized diethyl ether.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060519
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  • 2
    Electronic Resource
    Electronic Resource
    Development of an amperometric enzyme biosensor for the determination of the antioxidant tert-butylhydroxyanisole in a medium of reversed micelles (1996)
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 529-533 
    Details
    ISSN: 1040-0397
    Keywords: Tyrosinase electrode ; Reversed micelles ; Flow injection ; Phenolic antioxidants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A biocdtalytic scheme, based on the enzyme tyrosinase, has been developed for the determination of the antioxidant tert-butylhydroxyanisole (BHA) in food samples. Reversed micelles formed with ethyl acetate as organic solvent, dioctyl sulfosuccinate (AOT) as emulsifying agent, and phosphate buffer of pH 7.4 as aqueous phase, has been employed as the working medium. The potential applied to the tyrosinase electrode, as well as the temperature of the working reversed micelle, the percentage of aqueous phase, and the pH of the phosphate buffer solution have been optimized. The stability of the enzyme electrode with time has been also evaluated. A very good selectivity has been found with respect to potential interference from other substances commonly present in commercial antioxidant mixtures in food. An Eastman-AQ/enzyme immobilization approach has been employed to improve the stability of the tyrosinase biosensor in reversed micelles flowing streams. A flow injection method with amperometric detection for the determination of BHA has been developed and applied to the analysis of this antioxidant in commercial biscuits.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140080606
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