Hypochlorite reactions with phenols

C. Ammonia can be determined spectrophotometrically by reaction with phenol in the presence of hypochlorite (OC1) ... 

The reaction catalyzed by asparaginase (glutami-nase) is shown in Table 2. The ammonia released is used to monitor enzyme activity. It can be detected spectrophotometrically by the classical color analytical reaction with phenol and sodium hypochlorite, or... 

Ammonium ion is one of the inorganic species most frequently determined by UV-visible spectrophotometry. It is freed by the Kjeldahl method from organic matter and can be spectrophotometrically determined by reaction with phenol and hypochlorite in the presence of nitroprusside ion, with which it yields a blue compound (indophenol) with an absorbance maximum at 625 nm. Another alternative, especially avoiding the use of phenol, is by measuring the absorbance at 660 nm of an indophenol blue derivative generated by the reaction of ammonium ion with sodium salicylate in the presence of hypochlorite ion. These procedures are routinely used for the determination of ammonium ion with autoanalyzers. 

Urea gives a yellow color with / -dimethylaminobenzaldehyde (6), a positive biuret reaction (p. 271), a color reaction with sodium nitroprusside in alkaline media in the presence of ammonium persulfate (red color) (7), a color reaction with phenol and sodium hypochlorite (8), a very sensitive reaction with phenylhydrazine and aniline (9), and a reaction with xanthydrol (10). 

Reaction with 1,3-benzenediamine-periodate (91) or with a hypochlorite—alkaline phenol (Berthelot) reagent enables the detection of both 2- and 4-aminophenol, the latter reagent giving distinguishable blue and dark green products, respectively (92). 4-Aminophenol itself has been shown to react in alkaline solution with both the 2- and 3-aminophenol isomers, a reaction exploited for their detection (93). 

Available Chlorine Test. The chlorine germicidal equivalent concentration test is a practical-type test. It is called a capacity test. Under practical conditions of use, a container of disinfectant might receive many soiled, contaminated instniments or other items to be disinfected. Eventually, the capacity of the disinfectant to serve its function would be overloaded due to reaction with the accumulated organic matter and organisms. The chlorine germicidal equivalent concentration test compares the load of a culture of bacteria that a concentration of a disinfectant will absorb and still kill bacteria, as compared to standard concentrations of sodium hypochlorite tested similarly. In the test, 10 successive additions of the test culture are added to each of 3 concentrations of the hypochlorite. One min after each addition a sample is transferred to the subculture medium and the next addition is made 1.5 min after the previous one. The disinfectant is then evaluated in a manner similar to the phenol coefficient test. For equivalence, the disinfectant must yield the same number of negative tubes as one of the chlorine standards. 

Ammonia reacts with hypochlorite to form monochloroamine. The latter reacts with phenol to form an intensely blue compound, indophenol. The reaction is catalyzed by MnS04. The reaction steps are as follows ... 

Onodera et al. [8] examined the applicability of isotachophoresis to the identification and determination of chlorinated mono- and dicarboxylic acids in chlorinated effluents. Four electrolyte systems for the separation of acids were evaluated. The potential unit values in each system were determined for the chlorinated acids. A mechanism for the reaction of phenol with hypochlorite in dilute aqueous solutions is suggested, based on results from the isotachophoretic analysis of diethyl ether extracts taken from phenol treated with hypochlorite. 

Ammonia has been measured by using phenol and hypochlorite to form 4-(4-oxocyclohexadienylimino)phenol (indophenol) (15). Ruzicka and Hansen (15) also discussed a sensitive method that uses a gas-diffusion cell to transfer ammonia from the sample stream to an acid-base indicator stream. Urea can be determined as ammonia after reaction with urease... 

The phenol-hypochlorite (Indophenol-blue) method was used for ammonia analysis (Solorzano, 1969). Appropriate sample sizes were fixed with phenol within 24 hours of collection (Degobbis, 1973) and stored at all times at 4 C. Analyses were made within 2 weeks of collection. The reagent dilutions given by Presley (1971) were used, but the quantity added was doubled. All reaction and color development was done in polyethylene scintillation vials. Color development was allowed for 6-8 hr to obtain a straight-line standardization curve blanks (always <0.010 absorbance with respect to distilled water, 1-cm cell) were insignificant compared to sample absorbances and precision better than 3%. Standards were diluted immediately before use. 

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