Comparison of various colorimetric determinations of phenols

The determination of small quantity of phenols has been important, not only in some chemical industries such as the high-polymer industry, but also to the industrial waste-water problem. Considerable researches have been carried out in nephelometry and various photometric methods. The author has taken three methods, i. e. the p-nitroaniline, the nitronizing, and the 4-aminoantipyrin methods, for a comparative study of their application to colorimetric analysis. The results showed that the 4-amino method is most fitted for use particularly in the case of 2 ppm or less phenol content, and the nitronizing method for the analysis of phenol mixtures, while the nitroaniline method has an advantage in its simplicity of operation. However, with respect to both precision and speed of operation, the 4-amino method seems to be the one best suited for the determination of small amounts of phenols in water.