Iron is an abundant, naturally-occurring element found in soils, streams, surface waters, and groundwater.  High levels of iron in drinking water can cause objectionable taste and can stain plumbing and laundry. Iron in drinking water and wastewater is regulated by the EPA and other regulatory bodies. For samples that contain complexed or chelated iron or suspended iron, such as typical wastewater samples, digestion of the sample is required to allow all of the iron to react with the reagent. The Total Iron method measures all forms of iron, including ferrous, ferric, dissolved, suspended and complexed iron.

The HI96778-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents use an adaptation of Standard Methods for the Examination of Water and Wastewater, 23rd Edition, 3500-Fe B, Phenanthroline Method. Digestion of the sample with sulfuric acid and persulfate liberates iron from organic and inorganic complexes. After digestion, the iron reacts with 1,10-phenanthroline to form an orange-red complex.