Spectrophotometric Determination of Hydroxyl Radical

Abstract

The determination of hydroxyl radical (-OH), which was generated by the Haber-Weiss reaction of hydrogen peroxide using bis(ethylenediamine)copper(II) sulfate([Cu(en)₂]SO₄)as a catalyst, was investigated by the thiobarbituric acid (TBA) method spectrophotometrically. The determination of OH is carried out as follows: take 0.2 cma of 0.38 mM [Cu(en)2]2+ solution, 0.9 cm3 of pH 7.4 buffer solution, and 0.5 cm' of 45 mM 2-deoxy- Dribose solution in the test tube of about 30 cm3, and further add 0.2 cm3 of the same buffer solution (in the case of studing the inhibitor of OH reaction, the sample solution is added instead of the buffer solution) and 0.2 cm3 of 11202 solution (concentration, <0.1 mM); after incubating this solution for 5 h at 40 °C, add 12 cm3 of about 70 mM TBA and make to 15 cm3 the total volume by adding 1 cm3 of about 2 M HC1 to adjust the pH below 2.5; put this solution in boiling water for 30 min and after standing for 1 h at 25 °C, measure the absorbance at the wavelength of 532 n m.1, 1, 3, 3-Tetramethoxypropane was used as the standard substance of OH determination. This procedure can be applied to the research of the catalysis of metal complexes which allows to generate OH from 1-1202.