Colorimetric determination of aqueous nitrate concentration

Patent metadata

Field	Value
Publication number	US-10203316-B2
Application number	US-201615223781-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jul 29, 2016
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

A method of measuring nitrate concentration in an aqueous sample include mixing the aqueous sample with a water-soluble thioether compound including a chromophore group in the presence of a water soluble catalyst; measuring a color change, and correlating the color change to nitrate concentration.

First claim

What is claimed is:

1. A method of measuring nitrate concentration in an aqueous sample, comprising:
a. mixing the aqueous sample with a water-soluble thioether compound including a chromophore group in the presence of a water soluble catalyst, wherein the water-soluble thioether compound comprises a polyalkyleneoxide group, wherein the chomophore group is selected from the group consisting of a hydrophilic diarylmethane chromophore, a hydrophilic triarylmethane chromophore, a hydrophilic xanthene chromophore, a hydrophilic boron-dipyrromethene chromophore and a hydrophilic pyrene chromophore,
b. measuring a color change, wherein the color change is responsive to a nitrite concentration within the aqueous sample, and
c. correlating the color change to nitrate concentration, the correlating comprising correlating the nitrite concentration measured via the color change to a nitrate concentration.

2. The method of claim 1 wherein the water-soluble thioether compound is chosen to oxidize in the presence of nitrate.

3. The method of claim 2 wherein the water-soluble thioether compound has the formula:
R 3 —S—R 2 ,

wherein R 3 is a hydrophilic chromophore group and R 2 is the polyalkyleneoxide group.

4. The method of claim 3 wherein the hydrophilic chromophore group comprises a residue of a water-soluble conjugated chromophore.

5. The method of claim 3 wherein the hydrophilic chromophore group comprises a residue of a water-soluble, substituted aromatic chromophore.

6. The method of claim 3 wherein the polyalkyleneoxide comprises 4 to 5000 carbon atoms.

7. The method of claim 1 wherein the water soluble catalyst comprises MoO 2 Cl 2 (L) 2 wherein L is a hydrophilic group.

8. The method of claim 7 wherein L comprises a water soluble phosphine.

9. The method of claim 8 wherein L is trisulfonated-triphenylphosphineoxide.

10. The method of claim 7 wherein the water soluble catalyst further comprises a Cu 2+ co-catalyst.

11. The method of claim 1 wherein the color change occurs in the visible light spectrum.

12. The method of claim 11 wherein the color change occurs between a wavelength of 500 nm and 700 nm.

13. The method of claim 1 wherein the measuring of the color change is measured using a device selected from the group consisting of spectrometer, colorimeter, photometric device, color disc, and color block.

14. The method of claim 1 wherein a detection range of nitrate is between about 0 ppmw and 15 ppmw.

Assignees

• Hach Co

Inventors

• Macfarland Darren Kent
• Young Brendan Easley

Classifications

• Y10T436/173076

  Nitrite or nitrate · CPC title

• B01J31/2404

  Cyclic ligands, including e.g. non-condensed polycyclic ligands, the phosphine-P atom being a ring member or a substituent on the ring · CPC title

• B01J2231/70

  Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues · CPC title

• G01N33/182 Primary

  Specific anions in water · CPC title

• B01J31/1875

  Phosphinites (R2P(OR), their isomeric phosphine oxides (R3P=O) and RO-substitution derivatives thereof) · CPC title