Determination of submicrogram quantities of iron(III) by a catalytic polarographic method

A simple and sensitive polarographic method has been developed for the determination of submicrogram quantities (0.01-0.16 mug/ml) of iron('III) based on the catalytic polarographic reduction of bromate in presence of resacetophenone isoniazid hydrazone. A 200-fold ratio of Mg(2+), Ca(2+), Cr(3+), Mn(2+), Co(2+), Ni(2+), Zn(2+), Al(3+) to Fe(3+) does not interfere. However, Cu(2+) and Cd(2+) interfere if they are present in more than 20-fold ratio to Fe(3+). Ti(4+), V(5+), Mo(6+) and W(6+) interfere even at 5-fold ratio. There is no interference from F(-), Cl(-), Br(-), I(-), SO(2-)(4), NO(-)(3) or NO(-)(2) even when present in large excess, but EDTA, CN(-), SCN(-), C(2)O(2-)(4), citrate and tartrate suppress the wave to a marked extent.