The HI38040-100 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate iron measurements with the chemical test kit. These reagents follow the phenanthroline method to determine iron (Fe²⁺ and Fe³⁺) concentration.

For determination of iron, all ferric (Fe³⁺) ions are reduced to ferrous (Fe²⁺) ions before the phenanthroline reagent is added to the sample. The reaction between ferrous ions and the reagent causes an orange colored complex to form; the greater the concentration, the deeper the color. A Checker Disc is included for an accurate, side-by-side, visual analysis to determine iron concentration. These reagents are designed to be used with samples that have an expected iron range of 0.0 to 5.0 mg/L (ppm) iron.