Determination Of Volatile Phenolic Compounds In Water Samples By Sequential Injection Spectrophotometry

Volatile phenolic compounds are toxic organic substances to human health and the biotic environment, which are strictly regulated by both China and International commumities. Therefore, the development of sensitive, simple and fast methods for their determination is highly demanded, especially for environmental water quality monitoring.The first section of the dissertation reviewed of the current situation for water quality monitoring and the analytical methods for the determination of volatile phenolic compounds. In addition, the application of sequential injection in water quality monitoring is also discussed.The second part of the dissertation developed a sequential injection on-line distillation procedure for the determination of volatile phenolic compounds with detection by spectrophotometry, by taking the advantages of sequential injection system in terms of rapidness, repeatability, minimized sample consumption and cross contamination as well as automation. A 2.5mL sample solution was used for on-line distillation, and the distillate reacts with 4-aminoantipyrine and potassium ferricyanide to form a red substance in NH3-NH4Cl buffer solution. The absorbance of the reaction product is proportional to the concentration of phenol in the range 0.05-8.0 mg/L, giving rise to a detection of 0.01 mg/L. The relative standard deviation is 1.5% at the concentration level of 2.0 mg/L. The method was applied to the determination of volatile phenolic compounds in waste waters and the recoveries are within the range of 96%-106%.The last part of the dissertation developed a procedure for per-concentration of low level of volatile phenolic compounds by employing solid-phase extraction in a sequential injection system with detection by spectrophotometry. The red substance which was formed by the reaction of phenol and 4-aminoantipyrine and potassium ferricyanide in NH3-NH4Cl buffer solution can be efficiently adsorbed by an Amberlite XAD-7 resin packed microcolumn, which can be afterwards effectly by a small amount of ethanol. With a sample loading volume of 4 mL, a linear range of 0.004-0.3 mg/L was obtained, with a detection limit is 0.002 mg/L, A relative standard deviation of 1.4% is achieved at 0.1 mg/L. The procedure was applied to the determination of low volatile phenolic compounds in water samples and spiking recoveries within 96%-102% were obtained.In the last section, a summary for content of the experimentation was described.