Chromium (III) is an essential element for humans and can be metabolized in the body. Chromium (III) is found naturally in fruit, vegetables, meat and grains. Chromium (VI) has been identified as a carcinogen and can alter genetic material. Chromium (VI) is discharged from steel and paper mills or through the oxidation of chromium (III). Chromium (VI) has been a regulated drinking water contaminate since the 1940s, the US EPA only regulates total chromium.

The HI96781-25 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, 4500 ClO2 D method. The chromium in the sample is oxidized to hexavalent chromium during digestion. The hexavalent chromium reacts with the Diphenylcarbazide to form a red color proportional to the amount of chromium in the sample. This method has a strong temperature and pH dependence. The sample temperature must be between 18 and 22°C and the pH between 3 and 9.