Ammonia Berthelot reaction

The analysis target was the detection of ammonia in aqueous solutions, e.g. in surface water [114-116], The Berthelot reaction scheme was employed to monitor ammonia, by chemical conversion to indophenol blue, using a chlorination step first followed by coupling of two phenol moieties. The absorption of the dye was measured by a photometric-type experiment. Full conversion by efficient mixing is mandatory for a good analysis. 

Creatinine deaminase (EC 3.5.4.21 creatinine imino-hydrolase) catalyzes the conversion of creatinine to N-methylhydantoin and ammonia. Early methods concentrated on tlie detection of ammonia using either glutamate dehydrogenase or the Berthelot reaction. An alternative approach involves the enzyme N-methylhydantoin amido-hydrolase (Figure 24-l,D). ... 

Successful attempts have been made to replace titration by direct colorimetric determination of ammonia. Berthelot s reaction has been carried out on the neutralized Kjeldahl digest (E6, L19), but interference by H2O2 and by Ca++ can occur (R13). The Berthelot reaction has been speeded up by the introduction of a catalyst, sodium nitroprusside (L19) it must be carried out at pH 10-12 (C5) under which conditions it is specific for NH4+ (W12). The reaction between NH4+ and indanetrione hydrate may also be used the digest is neutralized, buffered at pH 5.0, heated with the reagent at 110°C for 30 minutes, diluted with 50% ethanol, and the color measured at 570 nm (Jl). 

Ammonia Cigarettes Ultrasound-assisted bleaching UV—Vis 0.05 pg mL-1 Flow injection system with a pervaporation unit iterative change of flow direction for improving extraction Berthelot reaction [415]... 

Ammonium is determined in many laboratories in a CF system in which the Berthelot reaction is implemented. In the Berthelot reaction, ammonium reacts with chlorine and phenol in the presence of sodium nitroprusside as catalyst in alkaline medium. EDTA is added to prevent interference of calcium and magnesium. Modern systems have been developed that use macroporous polytetrafluoroethylene (PTFE) membranes. In these systems a sample is introduced into a stream to which sodium hydroxide solution is added. Ammonia diffuses through the PTFE membrane into a stream of de-ionized water and the stream is fed through the flow-through cell of a conductivity meter. In this system a minimum of reagents is required and the only interference is from volatile amines. 

The determination is based on the Berthelot reaction, in which a phenol derivative (here salicylate) forms an azo dye in the presence of ammonia and hypochlorite. In alkaline medium, the indophenol thus formed has a green-blue colour, of which the absorbance is measured at a wavelength of 660 nm. This is a measure for the concentration of ammonium, formed by the nitrogen compounds in the sample. 

Krom, M. 1980. Spectrophotometric determination of ammonia a study of modified Berthelot reaction using salicylate and dichloroisocyanurate. The Analyst April 1980. 

M. Berthelot. found that many nitrogenous organic compounds furnish ammonia when heated with hydriodic acid and J. Kjeldahl showed that the nitrogen of many nitrogenous compounds is all converted into ammonia or ammonium sulphate when heated with cone, sulphuric acid—in the case of nitro-eompounds and cyanides the reaction is not always quantitative. The reaction proceeds more satisfactorily in the presence of mercury or mercuric oxide, copper, potassium hydrosulphate, sugar, phenol, benzoic acid, and analogous compounds. This reaction has been discussed by C. Arnold, A. Atterberg, C. Budde and C. V. Sehon,... 

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