Interference in Determination of Ammonia with the Hypochlorite-Alkaline Phenol Method of Berthelot

Article abstract of DOI:10.1021/ac00238a015

The blue color resulting from the formation of indophenol in the Berthelot method of determining ammonia was supressed by primary and secondary amines, sulfides, thiols, and ascorbic acid, and to lesser extent by tertiary amines.We postulate that nucleophilic additions of amines, thiols, and other nucleophiles to the quinoid intermediates of the Berthelot reaction decrease the formation of indophenol.It is also possible that reducing agents deplete hypochlorite to suboptimal levels.