Phenol (hydroxy-benzene) is the simplest of a group of similar organic chemicals which includes cresols, xylenols and catechols. Many of these "phenolics" are used as raw materials in the manufacture of polymers, plasticizers, hydraulic fluids and various industrial chemicals. Phenol itself is a common ingredient of disinfectants.

In drinking water, low-level phenolic concentrations impart a foul taste and odor, especially upon chlorination. High phenol concentrations can indicate contamination from industrial effluents or waste discharge.

The method is not applicable to the determination of trace levels. It is applicable to the monitoring of phenolic compounds in wastewater.

The Colorimetric Method. The well established 4-aminoantipyrine method is employed. Phenolic compounds react with 4-AAP in alkaline solution in the presence of ferricyanide to produce a red reaction product. Phenol, meta- and ortho-substituted phenols and some para-substituted phenols, under proper pH conditions, will register with this method. Results are expressed as ppm (mg/L) phenol.