Kinetic micro-determination of manganese in natural waters and of iridium, nitrilotriacetic acid and 1,2-diaminocyclohexane-NNN′N′-tetraacetic acid
Abstract
An automatic kinetic spectrophotometric method is described for the ultramicro determination of manganese and iridium, based on their catalytic effect on the periodate-phosphinate reaction. The method is also used for the determination of nitrilotriacetic acid (NTA) and 1,2-diaminocyclohexane-NNN′N′-tetraacetic acid (DCTA), on the basis of their activating and inhibiting effect, respectively, on the manganese-catalysed periodate-phosphinate reaction. The time required for the reaction to consume a fixed amount of periodate is measured automatically and related directly to the concentration of catalyst, activator or inhibitor. Manganese and iridium at the 10–8–10–7M level and NTA and DCTA at the 10–6M level were determined with average errors of about 2%. The method has been applied to the determination of manganese in natural waters.