AUTOMATED COLORIMETRIC MICRODETERMINATION OF PHENOLS BY OXIDATIVE COUPLING WITH 3-METHYL-2-BENZOTHIAZOLINONE HYDRAZONE

The previously reported oxidative coupling reaction of phenols with 3-methyl-2-benzothiazolinone hydrazone is the basis for a new automated general method for the determination of phenols. Conditions are also given for performing the method manually to compare it with other known methods. The widely used 4-aminoantipyrine method for phenols suffers in that many p-substituted phenols are not detected. The present method, however, is less dependent on the position of substituent groups. Furthermore, most of the phenols tested are determined at lower concentrations than are possible by the 4-aminoantipyrine method. Some phenols are determinable even in the parts-per-billion range without prior concentration-extraction into organic solvents. The system operates at a rate of 20 samples per hour alone or when combined with automated steam distillation of the phenols prior to the colorimetric reaction. For monitoring water supplies for phenols, the steam distillation step should usually provide the only cleanup necessary. For other purposes e.g., determination of pesticide residues which contain hydrolyzable phenol moieties preliminary sample treatment procedures will be required. © 1969, American Chemical Society. All rights reserved.