A simple electrochemical method for the determination of hydroxyl free radicals without separation process

Generally speaking, measurement of hydroxylated radical products of salicylic acid requires a fussy separation process. In this study, we describe a simple method to electrochemically detect hydroxyl radicals ((OH)-O-center dot) using 4-hydroxybenzoic acid (4-HBA) as the (OH)-O-center dot trap. The (OH)-O-center dot is generated by the Fenton reaction from iron (II) sulfate and hydrogen peroxide in a phosphate buffer solution. Experimental results show that our method can detect the (OH)-O-center dot with high sensitivity without any separation process. The differential pulse voltammetric responses show a linear dependence on the concentration of (OH)-O-center dot in a range of 2.0 x 10(-6) and 1.0 x 10(-3) M with a determination limit down to 5.0 x 10(-7) M. As a demonstration, the kinetics of the Fenton reaction was mapped by measuring the reaction product of hydroxyl radical trapped by 4-HBA. The result is in good agreement with that reported previously. All the results show that the present approach could provide a simple, inexpensive and promising method for biomedicine and iatrology. (c) 2007 Elsevier B.V. All rights reserved.