Alternative reagents for the improvement of the spectrophotometric method of phenol analysis

Two new compounds are studied as alternatives for replacing 4-aminoantipyri ne in the spectrophotometric analysis of phenols. 4-amino-1,2-diphenyl-5-me thylpyrazol-3-one and 4-amino-2,5-diphenyl-1-methylpyrazol-3-one show good analytical characteristics such as sufficient reproducibility and satisfact ory detection limits when used for the analysis of phenols. In addition, th e proposed methods respond highly to monochloro- and dichlorophenols and ar e therefore more representative for the analysis of phenols of anthropogeni c origin.