Please follow these researchgate links.

https://www.researchgate.net/publication/279564332_Improvement_of_the_Ammonia_Analysis_by_the_Phenate_Method_in_Water_and_Wastewater

https://www.researchgate.net/publication/262963081_Comparison_of_Phenate_and_Salicylate_Methods_for_Determination_of_Total_Ammonia_Nitrogen_in_Freshwater_and_Saline_Water

Article Improvement of the Ammonia Analysis by the Phenate Method in...

Article Comparison of Phenate and Salicylate Methods for Determinati...

Please check these pdf attachments also.

Dear Ma.Roselette Laserna Alojado,

Liquefied Phenol is: Phenol maintained in a liquid condition by the presence of about 10 percent of water. It contains not less than 89.0 percent by weight of C6H6O. It may contain a suitable stabilizer. Caution—Avoid contact with skin because serious burns may result.

http://www.pharmacopeia.cn/v29240/usp29nf24s0_m63530.html

Hoping this will be helpful,

Rafik

Colorimetric Determination of Ammonium (NH4+) in Solution

(ver. 960129)

There are several colorimetric methods available for determining NH4+ concentrations in water samples, soil extracts and plant digests. These methods all detect both NH4+ and NH3 forms of N. The method we will use is called "the indophenol blue method" or "phenate method." It is based on the reaction of NH3 in alkaline solution with phenate to produce a blue color (indophenol blue) in the presence of a strong oxidizing agent, such as hypochlorite. Although the reaction will proceed at room temperature, it can be sped up by heating the solution (35oC) and/or using a metal-containing catalyst such as sodium nitroferricyanide (nitroprusside). Many modifications of this method are available. The one we will use is based on Solorzano (Limnol Oceanogr. 1969. 14:799-801), modified for a 10 ml sample volume.

Other modifications of this method can be found in Methods of Soil Analysis (Page et al., eds., American Society of Agronomy, Inc. and Soil Science Society of America, Inc., Madison, WI), Methods of Seawater Analysis (Verlag Chemie; not in our library and may be hard to find) and Standard Methods for the Examination of Water and Wastewater. (Clesceri et al., eds., American Public Health Association, Washington, DC).

The phenate method also has been adapted for use on various automated analyzers, such as those manufactured by Technicon, Alpkem and Lachat. See the manual for the specific machine you are using.

Notes:

Use test tubes which can accommodate a 10 ml sample. All glassware should be very clean (scrubbed with hot water, rinsed with 0.1N HCL, rinsed 6 times with purified water, and rinsed once with reagent grade deionized water). Be sure water for reagents and standards is ammonia free. Ordinary distilled water may contain ammonium- use freshly deionized water.

Ammonia is volatile and is present in the air. Many different sources of ammonia can contaminate the samples. Smoking, ammonia detergents, freshly cut grass, opening a bottle of ammonium hydroxide in the laboratory, etc. Exercise caution.

Very turbid sample may need to filtered or centrifuged prior to analysis. Precipitation of calcium and magnesium hydroxide can interfere with the analysis. This can be prevented by addition of a complexing reagent such as citrate or EDTA. See Methods of Soil Analysis for further details (Page, A.L., R.H. Miller and D.R. Keeney, eds. 1982. Methods of Soil Analysis. American Society of Agronomy, Inc., Madison, WI)

Stock Reagents:

1) Phenol-alcohol reagent: dissolve add 10 g of phenol in 95% ethyl alcohol to a final volume of 100 ml (toxic- handle with care).

2) Sodium nitroprusside (nitroferricyanide): dissolve 1 g in DI water to a final volume of 200 ml. Store in dark bottle for not more than 1 month. (toxic)

3) Alkaline complexing reagent: dissolve 100 g of trisodium citrate and 5 g of sodium hydroxide in DI water to a final volume of 500 ml.

4) Sodium hypochlorite: use commercial bleach (i.e., Chlorox), as new as possible.

5) Oxidizing solution: add 100 ml alkaline solution (3) to 25 ml sodium hypochlorite (4). Prepare fresh daily.

Calibrants:

Stock Solution A- 1000 ppm NH4-N stock. Dissolve 4.7168 g of dry (110oC for 12 h) (NH4)2SO4 in approximately 900 ml of DI water in a 1 L volummetric flask. Bring to 1 L with DI water. Can be preserved by adding two drops of chloroform. Label with the solution, the date and your initials.

Stock Solution B- 100 ppm NH4-N stock. Transfer 10 ml of Stock solution A to a 100 ml volummetric flask. Dilute to mark with DI water. Label with the solution, the date and your initials.

Working standards (can be adjusted to cover the range of samples being analyzed). Using 100 ml volummetric flasks, prepare the following series of working standards.

Volume of Stock B Vol. of standard Concentration

1 ml 100 ml 1000 µg NH4-N/L

750 µl 100 ml 750 µg NH4-N/L

500 ml 100 ml 500 µg NH4-N/L

200 ml 100 ml 200 µg NH4-N/L

100 ml 100 ml 100 µg NH4-N/L

50 ml 100 ml 50 µg NH4-N/L

0 ml 100 ml 0 µg NH4-N/L

Assay:

1. Add 10 ml of standard or sample to labeled test tubes.

2. To all tubes add 0.4 ml (400 µl) of phenol solution (1), 0.4 ml nitroferricyanide (2) and 1 ml oxidizing reagent (5). (Note- volumes can be adjusted according to sample size)

3. Mix well (invert screw cap tubes). Let develop for at least 1 h (3 h is better) in darkness. Mix samples periodically while development is occurring.

4. Read absorbance of standards and unknown samples using a spectrophotometer set to 630 nm.

5. Use absorbance values of standards to generate a standard curve. Calculate concentrations in unknowns from standard curve.

6. Dispose of all assay waste into a labeled bottle -DO NOT PUT PHENOL DOWN THE SINK!

Limitations:

The detection limit is reported to be about 10 µg NH4-N/L and Beer's law is obeyed up to about 500 µg NH4-N/L. We have found that the method is linear to at least 750 µg NH4-N/L, and Koroleff (1976) reports that higher concentrations, up to 1200 µg NH4-N/L, can be measured with a one cm flow cell and an appropriate standard curve.

Sample preparation and storage:

Turbid samples and soil extracts will need to be filtered or centrifuged prior to analysis. If filtration is used, beware of ammonium contaminated filters (Whatman 42 is not acceptable). We have had success with Poretics polycarbonate membrane filters (0.4 µ pore size).

Samples should be stored in glass or polyethylene, and kept refrigerated until analyzed. Ammonium is very labile and samples should be analyzed as soon as possible (preferably within 7 days). Do not freeze samples before analysis. If necessary, samples may be preserved by addition of 0.8 ml conc. H2SO4 to pH

yes you should dissolve it wirh ETOH 95% but aviod to contact with it.

In a fume hood, dissolve 20 g of crystalline analytical reagent grade

phenol in 100 mls of 95% v/v ethyl alcohol (or 22 mls 90% Phenol  in 200 ml 95% ETOH). This solution is stable for several months.

and also you can see the methods for deterimnation the nutrients ain strickland book for practial sea water analysis and you will find how to preprae it clearly.

https://epic.awi.de/39262/1/Strickland-Parsons_1972.pdf

http://www.agroecologylab.com/uploads/2/7/2/8/27281831/ammonium-solorzano.pdf

kind regards

Mohamed Hassaan

Dear Hassaan, I am bit confused at some places in literatures author has mentioned 1) In a fume hood, dissolve 20 g of crystalline analytical reagent grade

phenol in 100 mls of 95% v/v ethyl alcohol (or 22 mls 90% Phenol  in 200 ml 95% ETOH). This solution is stable for several months.

and as per your suggestion you said

2) In a fume hood, dissolve 10 g of crystalline analytical reagent grade phenol in 100 mls of 95% v/v ethyl alcohol (or 22 mls 90% Phenol  in 200 ml 95% ETOH). This solution is stable for several months.

Can you please clarify which one is correct and why ?

Looking forward from you

Thanks

Dear Dr Jai Prakash Chaudhary when I read Parson 1972 (which was shared by Mohamed Hassan), it said, 20 g of crystalline analytical reagent grade phenol is added in 200 mls of 95% v/v ethyl alcohol. So if we use 10 g of crystalline analytical reagent grade phenol in 100 mls of 95% v/v ethyl alcohol this should be correct too.

Simply boiling is also the best solution ae 80°c for 10 minutes to convert crystal form into liquid.

Please avoid contact with skin and eyes.