Method of determining a concentration of nitrate
View Patent ↗A method of determining a concentration of nitrate includes mixing an acid with a first mixture comprising an aldehyde, a chloride and at least one of a nitrate sample and distilled water so as to obtain a second mixture. The second mixture is reacted with a phenol so as to develop a color in a third mixture after a reaction time. The concentration of nitrate is determined colorimetrically with the third mixture.
1. A method of determining a concentration of nitrate, the method comprising:
mixing an acid with a first mixture comprising an aldehyde, a chloride and at least one of a nitrate sample and distilled water so as to obtain a second mixture;
reacting a phenol with the second mixture so as to develop a color in a third mixture after a reaction time; and
determining the concentration of nitrate colorimetrically with the third mixture.
2. The method as recited in claim 1 , wherein:
the first mixture is obtained by mixing a first solution containing the aldehyde with a second solution containing the chloride to obtain an aldehyde-chloride solution and adding a third solution containing the at least one of a nitrate sample and distilled water to the aldehyde-chloride solution to obtain a fourth solution as the first mixture,
the second mixture is obtained by mixing the acid with the fourth solution so as to obtain a fifth solution as the second mixture, and
the third mixture is obtained by reacting a sixth solution containing the phenol with the fifth solution.
3. The method as recited in claim 1 , wherein the aldehyde is formaldehyde.
4. The method as recited in claim 3 , wherein the formaldehyde is provided as at least one of a solid, as a liquid/solution, as a gas, as a compound which will produce formaldehyde when reacting with the acid and the phenol, as a formaldehyde-releasing plastic, and as a formaldehyde-releasing antimicrobial chemical compound.
5. The method as recited in claim 4 , wherein the compound which will release formaldehyde when reacting with the acid and the phenol includes at least one of paraformaldehyde, hexamethylenetetramine, and sodium formaldehyde sulfoxylate, the formaldehyde-releasing plastic includes at least one of phenol formaldehyde resin, polyoxymethylene, and melamine resin, and the formaldehyde-releasing antimicrobial chemical compound includes at least one of 5-bromo-5-nitro-1,3-dioxane, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, imidazolidinyl urea, and DMDM Hydantoin.
6. The method as recited in claim 1 , wherein the chloride is an alkali chloride.
7. The method as recited in claim 6 , wherein the alkali chloride is at least one of lithium chloride, sodium chloride, potassium chloride, and rubidium chloride.
8. The method as recited in claim 1 , wherein the chloride is used in a concentration of 10 to 100,000 ppm.
9. The method as recited in claim 1 , wherein the acid has a pH<1.
10. The method as recited in claim 1 , wherein the acid is a mixture of sulfuric acid and phosphoric acid.
11. The method as recited in claim 1 , wherein the phenol is an unsubstituted or a substituted monophenol or a diphenol having at least a single aryl group, wherein a nitroso substitution is directed to the a para position.
12. The method as recited in claim 11 , wherein the phenol is at least one of 2,6-dimethylphenol (2,6 xylenol) and 4-ethyl resorcinol.
13. The method as recited in claim 1 , wherein the reaction time is up to 20 min.
14. The method as recited in claim 1 , wherein the color is at least one of red, reddish, pink, blue, bluish, and violet.
15. The method as recited in claim 1 , wherein the concentration of nitrate is colorimetrically determined by measuring an absorption of the third mixture with at least one of a photometric device and by comparing the color of the third mixture with a pre-determined color spectra.
16. The method as recited in claim 15 , wherein the pre-determined color spectra is at least one of a color disk and a color block.
17. The method as recited in claim 15 wherein the photometric device operates at a wavelength of from about 460 nm to about 540 nm.
18. The method as recited in claim 1 , wherein the method has at least one of an extrapolated detection limit of 6 μg/L and a limit of determination of 21 ppb.
19. A test kit for determining the concentration of nitrate, wherein the test kit uses the method as recited in claim 1 .
20. The test kit as recited in claim 19 , wherein the test kit further uses a second nitrate analysis method based on 2,6-dimethylphenol.