The HI3864-100 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate phenol measurements with the chemical test kit. These reagents follow the aminoantipyrine method to determine phenol concentration.

For determination of phenols, when the A reagent is first added and mixed and the B powder reagent is added, after a 10 minute reaction time, the reaction between phenols and the reagent causes a yellow-orange colored complex to form; the greater the concentration, the deeper the color. Two Checker Discs are included for an accurate, side-by-side, visual analysis to determine low range or high range phenol concentration. These reagents are designed to be used with low range samples that have an expected phenol range of 0.00 to 1.00 mg/L (ppm) and high range samples that have an expected range of 0.5 to 5.0 mg/L (ppm) phenols.