a highly sensitive differential pulse polarographic (dpp) method has been developed for the determination of trace amounts of osmium, based on the catalytic effect of osmium (viii) on the oxidation of pyrogallol red (pgr) by sodium bromate at ph 7.00 and 25.0 0.1 ? c. the reaction rate was monitored by measuring the differential pulse cathodic current of the oxidation product of pgr and bromate...