Selective indicator reaction for kinetic determination of traces of manganese(II), ribavirin and tiazofurin
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In this work it was established that, in the presence of ammonium carbonate, traces of manganese(II) catalyse the oxidation of Nile Blue A by hydrogen peroxide, which enables its: kinetic determination in the concentration range from 6.6 to 65.9 ng cm(-3), the detection limit being 8.0 x 10(-2) ng cm(-3). Antiviral/antitumour substances modify the catalytic activity of manganese (TT): 1-beta -D-ribofuranosyl-1,2,4-triazole-3-carboxamide, ribavirin, increases the catalytic effect of manganese(II), while 2-beta -D-ribofuranosyl-thiazole-4-carboxamide, tiazofurin, acts as an inhibitor. On the basis of these effects, a kinetic method for determining ribavirin concentrations from 0.5 x 10(-1) to 4.0 x 10(-1) mug cm(-3) and tiazofurin concentrations from 0.3 to 2.6 mug cm(-3) is proposed. The kinetics of the indicator reaction were studied ill the presence of the substances examined, the kinetic equations established, and the constants of the corresponding reaction rates calculated. The effe...ct of temperature on these reactions was also investigated. The method was applied to the determination of manganese(II) in mineral water and ribavirin in pharmaceutical preparations.