Phenol belongs to high toxic substances. The higher the degree of substitution of phenol, the greater the toxicity, the teratogenic and carcinogenic effect of methyl derivatives of phenol. The acute poisoning symptoms will appear when the human body takes a certain amount; Drinking water contaminated with phenol for a long time can cause dizziness, itching, anemia and nervous system disorders. When the phenol content in water is more than 5mg/l, it will cause fish poisoning and death. When chlorination and disinfection of water, phenols can react with chlorine gas to produce chlorophenols, which makes the water body produce obvious odor. The main pollution sources of phenol are oil refining, coking, gas generating stations, wood corrosion prevention and some industrial wastewater such as phenolic resin. Different phenols have different boiling points. Phenols can be divided into volatile phenols and non-volatile phenols by whether they can volatilize with water vapor. Generally, the volatile phenols with boiling point below 230 ℃ are volatile phenols, while those with boiling point above 230 ℃ are non-volatile phenols. The main analytical methods of phenol are brominated titration (gb7491-87), 4-antipyrine spectrophotometry (gb7490-87), chromatography, etc. Whether bromination titration or spectrophotometry, when there are oxidants, reducers, Oils and some metal ions in water samples, they should be eliminated and pre distilled. For example, the free chlorine is reduced by adding ferrous sulfate; Copper sulfate is added to sulfide to precipitate or escape in the form of hydrogen sulfide under acidic conditions; The oil is extracted and removed by organic solvent. The distillation has two functions: one is to separate volatile phenol, the other is to eliminate the interference of color, turbidity and metal ions.