STUDIES ON THE APPLICATION OF PHOTOCHEMICAL-REACTIONS IN A FLOW-INJECTION SYSTEM .1. DETERMINATION OF TRACE AMOUNTS OF NITRITE, BASED ON ITS INHIBITORY EFFECT ON THE PHOTOCHEMICAL-REACTION BETWEEN IODINE AND ETHYLENEDIAMINETETRAACETIC ACID

An automated procedure for the photochemical determination of nitrite has been developed, involving use of a laboratory-built flow-through photochemical reactor and a laboratory-built flow-through amperometric detector in a flow injection system, based on the inhibitory effect of nitrite on the photochemical reaction between iodine and ethylenediaminetetraacetic acid. Optimum analytical conditions were established. Nitrite can be determined in the range from 1 x 10(-7) to 4 x 10(-6) mol dm-3, with a sampling frequency of 60-80 h-1 and a relative standard deviation of less than 1%. The method has been applied to the determination of nitrite in natural water samples, and recoveries of at least 91% have been attained.