Nessler method

Ammonia Coulometry (e.g. Nessler method) Ion selective electrode Oxidation to NO and chemiluminescence... 

A recent study of the Conway method applied to whole blood (R2) stresses the importance of the ammonia derived from the breakdown of blood constituents in the highly alkaline diffusion medium and recommends a correction for this. It is suggested that two diffusions be performed, one for 40 and one for 80 minutes. The difference between the two values would represent the actual preformed ammonia of the blood. This problem has been discussed by others (B6, S3), as well as by Conway (C5). The requirement for a 40-minute diffusion in order to obtain a complete yield of ammonia from the sample is a major handicap of the Conway apparatus. The Seligson method requires only 10 to 20 minutes, resulting in much less time for artifact. The use of the titration of basic (R2) leads to the inclusion of much volatile base which is not ammonia, and much of the apparent formation of ammonia during diffusion is probably volatile amines, for it is not seen so constantly using Nesslerization methods. 

If, however, the precipitate of diphenylurea is too small to weigh accurately, it is converted to ammonia and determined colorimetrically by the Nessler method. In this procedure, the filter paper is removed from the funnel and placed in a small beaker 4 ml. pure sulphuric acid (66° Be) are added, allowing this to flow slowly over the platinum spiral and through the funnel so as to wash off all traces of adherent precipitate. To the mixture obtained in this way 10 mgm. mercuric sulphate are added and the whole is then kept near boiling temperature for 2 hours. After allowing to cool, 20 ml. distilled water are added and the mixture is transferred to a 200-ml. flask containing 0-25 gm. sodium thiosulphate dissolved in 100 ml. water to remove the mercury. The beaker is washed with water which is added to the contents of the flask until the total volume is about 150 ml. and the ammonia determined in this. 

Materials. Improved Kjeldahl-Nessler Method. Analyt. Chem. 20, 481 (1948). 

Two methods of similar sensitivity are commonly used for determining ammonia. These are the classical Nessler method and the indophenol method. The indophenol method is more convenient since the blue reaction product, which is the basis for the spectrophotometric measurement, is soluble in water. 

Chemical analysis Chemical analyses on suspension or powder samples were performed by a volumetric method (0.05 normal potassium dichromate) following dissolution in hydrochloric acid. The ferrous (Fe2+) content was determined directly. The ferric (Fe3+) content was analyzed via the Zimmermann-Reinhardt (SnCl2 reduction) technique, which gives the total iron. Subtraction of the Fe2+ gives the desired Fe3+ value. The Fe2+/Fe3+ ratio was determined with an accuracy of 0.01. The accuracy of the determination of the total iron was 0.5% of the result. Chloride content was determined by Volhard titration with an accuracy of 5% of the result. Nitrogen content was analyzed with the Nessler method with a relative accuracy of 15%. 

G.L. Miller, E.E. Miller, Determination of nitrogen in biological materials, improved Kjeldahl-Nessler method, Anal. Chem. 20 (1948) 481. 

In a later study,an ion mobility spectrometer equipped with a corona discharge ion source was used with pyridine as an alternate reagent gas to enhance selectivity and sensitivity for the determination of ammoniacal nitrogen in river and tap water samples. The limit of detection was about 9.2 x 10 pg/mL, and the linear dynamic range was obtained from 0.03 to 2.00 pg/mL. The RSD was about 11%, and analytical results on actual environmental samples compared favorably with the Nessler method. 

The same sample was then analyzed for protein by the modified Folin-Ciocalteu method." A correction was made for the color of the antigen. To test the method ten triplicate analyses were run on purified antibody samples by both the modified Folin-Ciiocalteu and the Nessler method by two analysts. The first method gave values which averaged 1.035 0.035 times the second. 

The colorimetric Nesslerization method uses alkaline phenol and hypochlorite to react with ammonia to form indophenol blue in an amount proportional to the ammonia concentration. The blue color is intensified with sodium nitroprusside, and the concentration is measured using a calibrated colorimeter. The titration of basic ammonia is accomplished with standard sulfuric acid using a mixed indicator. Determination of ammonia may also be based upon the indophenol reaction adapted to automated gas-segmented continuous flow analysis. Potentiometric determination of ammonia is performed by ion-selective ammonia electrodes. 

Ammoniacal nitrogen is usually determined by flow methods involving derivatization reactions for spectrophotometric determination. Berthelot (or indophenol blue) [99,115-119] and Nessler methods [120] are the two most important examples, both adopted for the quantification of ammonium ion in matrices as diverse as natural waters, wastewaters, atmospheric samples, food, soil extracts, plant material, and biological fluids. Measuring the fluorescence intensity produced by the reaction of the ammonium ion with OPA is another widespread method for the analysis of this ion [121-125]. 

Urease-Nesslerization methods. The ammonia formed by the urease reaction reacts with mercuric and potassium iodides in alkaline solution to give a yellow colour. However, this method has several disadvantages which has led to its gradual disuse. The major disadvantages are that ... 

Ammonia and ammonium ions in industrial water streams, including waste-water streams, can be determined by either of two methods (ASTM Procedure D1426). In the first, the sample is buffered to a pH of 7.4 and distilled into a solution of boric acid where the ammonia nitrogen is deterrnined colorimetricaHy with Nessler reagents or titrated using standard sulfuric acid. 

The other method is less accurate but more rapid and involves direct Nessleri2ation of the sample for colorimetric deterrnination. Other colorimetric indicators with more sensitivity, such as indophenol, have been used in place of Nessler s reagent. Ion-selective electrodes have also found use in analysis for trace ammonia (93). 

A. Standard series method (Section 17.4). The test solution contained in a Nessler tube is diluted to a definite volume, thoroughly mixed, and its colour compared with a series of standards similarly prepared. The concentration of the unknown is then, of course, equal to that of the known solution whose colour it matches exactly. The accuracy of the method will depend upon the concentrations of the standard series the probable error is of the order of + 3 per cent, but may be as high as + 8 per cent. 

B. Duplication method. This is usually applied as the so-called colorimetric titration in which a known volume (x mL) of the test solution is treated in a Nessler cylinder with a measured volume (y mL) of appropriate reagent so that a colour is developed. Distilled water (x mL) is placed in a second Nessler cylinder together with y mL of reagent. A standard solution of the substance under test is now added to the second cylinder from a microburette until the colour developed matches that in the first tube the concentration of the test solution can then be calculated. The standard solution should be of such concentration that it amounts to no more than 2 per cent of the final solution. This method is only approximate but has the merit that only the simplest apparatus is required it will not be discussed further. 

Procedure Bum 0.30 g, in three equal portions, by the method for oxygen-flask combustion (BP), using a 1 Litre flask and a separate 20 ml portion of DW as the absorbing liquid for each combustion, shaking the flask vigorously for about 15 minutes and transferring to the same 100 ml Nessler cylinder. Add 5 ml of acid zirconyl alizarin solution to the combined liquids, adjust the volume to 100 ml with DW and allow to stand for 1 hour. 

Ammonium chloride is analyzed by treatment with formaldehyde (neutralized with NaOH) and the product HCl formed is analyzed by titration using an acid-base color indicator such as phenolphthalein. Alternatively, it may be mixed with caustic soda solution and distdled. The distillate may be analyzed for NH3 by titration with H2SO4 or by colorimetric Nesslerization or with an ammonia-selective electrode (APHA, AWWA, WEF. 1995. Standard Methods for the Examination of Water and Wastewater. 19th ed. Washington, DC, American Pubhc Health Association). The presence of ammonia or any other ammonium compound would interfere in the test. The moisture content in NH4CI may be determined by Karl—Fischer method. 

Method 1. Place an amount of the sample, directed in the monograph, in a Nessler tube. Dissolve in water to make 40 mL. Add 2 mL of dilute acetic acid and water to make 50 mL, and designate it as the test solution. The control solution is prepared by placing the volume of standard lead solution directed in the monograph in a Nessler tube, and adding 2 mL of dilute acetic acid and water to make 50 mL. 

A JColorimetric Methods are applicable for detn of small quantities of AN such as 0.1-10 mg. This can be done by using one of the following reagents Nessler s (Refs 3 6), m-xylenol (Refs 5 12) or sulfanilic acid a-naphthylamine (Ref 6, p 140) B)Other Quantitative Methods. For larger... 

Jacobs (Ref 12) stated that AN is usually estimated in dusts by detg the NHS content of a sample either by nesslerization or by the m-xylenol reagent. When the dust also contains nitrocompds (such as nitrated derivs of toluene), it is necessary to make a disen in the presence of an alkali (as in the Kjeldahl method) and then test the distillate by one of the above reagents... 

Water-Soluble Sulfates, Chlorides, and Nitrates. The procedures are applicable to pigments and extenders. The choice of hot or cold extraction depends on the properties of the pigment and should be agreed. The anions are determined by the usual analytical methods. For standards, see Table 1 ( Sulfates , Chlorides , and Nitrates ). Apparatus Nessler tubes or spectrophotometer, equipment for pH measurement. 

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