Colorimetric determination of iron

Abstract

3-(2-pyridyl)-5,6-bis(phenylsulfonic acid)-1,2,4-triazine and certain salts thereof, e.g. sodium, are provided together with a method for forming such compounds. These compounds are useful as reagents in the spectrophotometric determination of iron in water or other solutions.

I claim as my invention: 
     
       1. In a method for quantitatively determining the presence of iron in a sample solution which includes adding a reagent to a sample solution containing iron in the ferrous state to form a colored complex and colorimetrically determining the iron content, the improvement comprising using 3-(2-pyridyl)-5,6-bis(phenylsulfonic acid)-1,2,4 triazine as the reagent .Iadd.to provide greater sensitivity as compared to that obtained with 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine.Iaddend.. 
     
     
       2. The method of claim 1 wherein the sulfonic acid groups are located at the 4-position.