Phenol-Hypochlorite Reaction for Determination of Ammonia

Analytical Chemistry (Impact Factor: 5.64). 07/1967; 39(8). DOI: 10.1021/ac60252a045


The Berthelot color reaction has been investigated with the particular aim of presenting a simple, reliable analytical procedure. The combination of two reagents prepared readily, phenol plus nitroprusside and alkali plus hypochlorite, gave excellent reproducibility with great convenience. After the ammonium sulfate sample was mixed with the phenol reagent the hypochlorite reagent could be added up to 30 minutes later without change of absorbance, whereas if this sample were mixed with a reagent containing hypochlorite or with alkaline phenate plus nitroprusside, there was a decrease in absorbance unless the second reagent was added immediately. Satisfactory color development with minimal precautions was given by a variety of reagent concentrations and by reaction temperatures of 20°, 25°, 37°, and 75° C. Sensitivity was increased at 75° C although the time to reach maximum absorbance was longer than at 37° C. The absorbance maximum was reached quickly at 100° C but this temperature is not recommended because the absorbance decreased rapidly thereafter.

372 Reads
  • Source
    • "The measurement conditions were: 40 @BULLET C; a mobile phase of 0.1% phosphoric acid; and a mobile phase flow rate of 1 mL min −1 . The ammonium was measured by the phenol-hypochlorite method [21]. The -PGA concentration was measured by cetylmethylammonium bromide (CTAB) method222324. "
    [Show abstract] [Hide abstract]
    ABSTRACT: tBacillus licheniformis TISTR 1010 was identified as a glutamic acid-independent producer of poly-�-glutamic acid (�-PGA) in a newly modified B medium in a shake flask culture. The fed-batch productionof �-PGA by this strain was optimized through simultaneously and continuously feeding glucose andNH4Cl with manual and pH-stat based feeding methods in a 7-L stirred fermenter. Using the optimizedoperation, the dissolved oxygen concentration, the pH, the glucose concentration and NH4Cl concen-tration could be stably controlled to extend the �-PGA production phase and eliminate the hydrolysisof �-PGA. As a result, the �-PGA concentration and productivity reached levels of 27.5 ± 0.2 g L−1and0.286 ± 0.059 g L−1h−1, respectively. These values of final concentration and productivity were 5-foldand 3-fold of those obtained without the optimization.
    Full-text · Article · Feb 2016
  • Source
    • "Extraction was carried out according to De Block et al. [11]. Ammonium nitrogen content was measured according to Weatherburn [12]. Water content was determined by drying for 24 h at 105 ∘ C. All data were subjected to analysis of variance (ANOVA). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Transformation of plants with genes encoding a glutamine synthetase (GS), a key nitrogen metabolism enzyme, is usually used to increase productivity. However, overexpression of these genes may increase resistance to phosphinothricin (PPT) that irreversibly inhibits GS causing ammonium accumulation in plant tissues. Transgenic plants of two birch ( Betula pubescens ) genotypes expressing a pine cytosolic GS gene were used for studying the PPT effect on trees. Two control and 8 transgenic lines were treated with herbicide “Basta” at dose equivalent to 2.5 and 5 Lha −1 . Necrosis and abscission of leaves occurred irrespective of a transgenic status or the treatment dose. Ammonium content in leaf tissue in 3 days after the 5 Lha −1 treatment was substantially increased in all plants, 3.2–16.0 times depending on line. After the 2.5 Lha −1 treatment, ammonium content in three transgenic lines was not different from that in control variant sprayed with water. The herbicide treatment caused more prominent desiccation in the bp3f1 genotype nontransgenic plants as compared to transgenic plants, but not in the bp4a genotype. Lack of correlation between ammonium levels and survival of transgenic plants suggests that ammonium toxicity is not a main reason for the birch plant death after the PPT treatment.
    Full-text · Article · Dec 2015
  • Source
    • "Urease inhibition assay. The urease inhibition activity was determined by measuring the amount of ammonia being produced using the indophenol method described somewhere (Weatherburn, 1967). The assay mixture, containing 10 μL of enzyme and 10 μL of compounds (25 μg/mL) in 40 μL buffer (100 mM urea, 0.01 M K 2 HPO 4 , 1mM EDTA, and 0.01 M LiCl 2 , pH 8.2), were incubated for 30 min at 37 °C in 96-well plates. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study was carried out to evaluate anti-Helicobacter pylori and its associated urease activity of labdane diterpenoids isolated from Andrographis paniculata. A molecular docking analysis was performed by using ArgusLab 4.0.1 software. The results obtained indicate that compound A possesses strong inhibition to H. pylori, 28 ± 2.98 (minimum inhibitory concentration, 9 µg/mL), and its urease, 85.54 ± 2.62% (IC50 , 20.2 µg/mL). Compounds B, C, and D also showed moderate inhibition to H. pylori and its urease. The obtained results were in agreement with the molecular docking analysis of compounds. The phytochemicals under investigation were found to be promising antibacterial agents. Moreover, the isolated compounds can be considered as a resource for searching novel anti-H. pylori agents possessing urease inhibition. Copyright © 2015 John Wiley & Sons, Ltd.
    Full-text · Article · Dec 2015 · Phytotherapy Research
Show more