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Physical Methods
Published in Jerome Greyson, Carbon, Nitrogen, and Sulfur Pollutants and Their Determination in Air and Water, 2020
Ammonia in water is determined by reacting the sample with a solution of potassium mercury iodide (Nessler’s reagent). The resulting brown solution is quantitated with a filter colorimeter using filters transmitting in the neighborhood of 425 nm. Ammonia may also be determined in water with a solution of sodium phenylate and sodium hypochlorite.* The reaction results in the formation of a colored solution of indophenol blue, the concentration of which is proportionalto the ammonia. Quantitation may be accomplished by measuring the absorption of the indophenol blue at 630-660 nm. Full descriptions of these methods, incidentally, may also be found in ASTM Standard D 1426.
Environmental Aspects and Analysis of Phenols in the Aquatic Environment
Published in B. K. Afghan, Alfred S. Y. Chau, Analysis of Trace Organics in the Aquatic Environment, 2017
Houghton and Pelly32 described a colorimetric method suitable for determination of phenols in water at concentrations of 10 ppb and above. The procedure involves a 200 ml aliquot of water sample and the use of diamine reagent. The resultant solution is titrated with sodium hypochlorite until the pale pink tinge disappears and the solution is starting to turn blue, indicating the formation of indophenol. The resultant solution is then extracted with carbon tetrachloride. The quantity of phenol in the sample is determined by visual color matching of the anhydrous carbon tetrachloride extract with the known quantities of phenol standards passed throueh the same procedure.
Nitrogen (Ammonia)
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
Ammonia reacts with hypochlorite to form monochloroamine. The latter reacts with phenol to form an intensely blue compound, indophenol. The reaction is catalyzed by MnSO4. The reaction steps are as follows:
Enzymatic crosslinking of silk sericin through combined use of TGase and the custom peptide
Published in The Journal of The Textile Institute, 2020
Xiaoxiao Guo, Qian Zhou, Ping Wang, Yuanyuan Yu, Jiugang Yuan, Qiang Wang
Determination of ammonia content has been studied extensively by the indophenol blue spectrophotometry (Sequeira et al., 2002). The method includes two chromogenic solutions, one is the mixture of 7 g/L sodium hypochlorite, 5 g/L sodium hydroxide and 4 g/L sodium citrate. Another is a mixture of 10 g/L phenol and 50 mg/L of sodium nitroprusside. During the process of the reaction, 5 mL of solution A, 5 mL of solution B, and 1 mL of ammonia standard solution were mixed uniformly, then incubated at 37 °C for 30 min. The reaction of ammonia with phenol and hypochlorite can form a blue indophenol-type compound that might be quantitatively measured by spectrophotometry at 637 nm. Linear relationship between the absorbance and ammonia content in ammonium sulfate was showed in Eq. (1). where C is the concentration of ammonia (μg/mL), A represents the absorbance at 637 nm, and the correlation coefficient is 0.99907.