SPECTROPHOTOMETRIC DETERMINATION OF HYDRO XYL RADICAL

The determination of hydroxyl radical (.OH), which was generated by th e Haber-Weiss reaction of hydrogen peroxide using bis(ethylenediamine) copper(II) sulfate([Cu(en)2]SO4) as a catalyst, was investigated by th e thiobarbituric acid (TBA) method spectrophotometrically. The determi nation of .OH is carried out as follows : take 0. 2 cm3 of 0. 38 mM [C u(en)2]2+ solution, 0.9 cm3 of pH 7.4 buffer solution, and 0.5 cm3 of 45 mM 2-deoxy-D-ribose solution in the test tube of about 30 cm3, and further add 0.2 cm3 of the same buffer solution (in the case of studin g the inhibitor of .OH reaction, the sample solution is added instead of the buff er solution) and 0. 2 CM3 of H2O2 solution (concentration, <0. 1 mM) ; after incubating this solution for 5 h at 40-degrees-C, a dd 12 cm3 of about 70 mM TBA and make to 15 cm3 the total volume by ad ding 1 cm3 of about 2 M HCI to adjust the pH below 2. 5 ; put this sol ution in boiling water for 30 min and after standing for 1 h at 25-deg rees-C, measure the absorbance at the wavelength of 532 nm. 1,1,3,3-Te tramethoxypropane was used as the standard substance of .OH determinat ion. This procedure can be applied to the research of the catalysis of metal complexes which allows to generate .OH from H2O2.