Method for determining concentration of polyelectrolytes and phosphonates

1. A method for determining concentration of polyelectrolyte or phosphonate in a sample comprising polyelectrolyte or phosphonate, the method comprising:

optionally diluting and/or purifying the sample;

admixing the sample with a reagent comprising a lanthanide(lll) ion;

admixing the sample with silica;

allowing the polyelectrolyte or phosphonate in the sample to interact with the reagent comprising the lanthanide(lll) ion and the silica;

exciting the sample at a excitation wavelength and detecting a sample signal deriving from the lanthanide(lll) ion at a signal wavelength by using time-resolved fluorescence measurement; and

determining the concentration of the polyelectrolyte or phosphonate in the sample by using the detected sample signal.

2. The method according to claim 1 , wherein concentration of the polyelectrolyte or phosphonate in the measurement mixture is in the range of 0.01500 ppm.

3. The method according to claim 2 , wherein concentration of the polyelectrolyte or phosphonate in the measurement mixture is in the range of 0.5-50 ppm.

4. The method according to claim 1 , wherein concentration of the silica in the measurement mixture is in the range of 0.05-200 ppm.

5. The method according to claim 4 , wherein concentration of the silica in the measurement mixture is in the range of 0.5-100 ppm.

6. The method according to claim 4 , wherein concentration of the lanthanide(III) ion in the measurement mixture is in the range of 0.1-50 μM.

7. The method according to claim 1 , wherein concentration of the lanthanide(lll) ion in the measurement mixture is in the range of 0.1-100 μM.

8. The method according to claim 1 , wherein the silica comprises silicic acid, silicates, oligomeric silica or a mixture thereof.

9. The method according to claim 1 , wherein the polyelectrolyte or phosphonate contains two or more groups capable of chelating with the lanthanide(III) ion, preferably selected from esters, ethers, hydroxyls, thiols, carboxylates, sulfonates, amides, phosphates, phosphonates and/or amine groups.

10. The method according to claim 1 , wherein concentration of phosphonic acid containing two or more groups capable of chelating with the lanthanide(III) is determined.

11. The method according to claim 10 , wherein the phosphonic acid is selected from hydroxyethylidene diphosphonic acid, aminotris(methylenephosphonic acid), ethylenediamine tetra(methylene phosphonic acid), and diethylenetriamine penta(methylene phosphonic acid).

12. The method according to claim 1 , wherein the lanthanide(lll) ion is selected from europium, terbium, samarium or dysprosium ions, preferably europium or terbium ions.

13. The method according to claim 1 , wherein a signal modifier is added to the sample before the excitation of the sample.

14. The method according to claim 13 , wherein the signal modifier comprises a metal ion selected from the group comprising copper, nickel, chromium, iron, gold, silver, cobalt, and any of their mixtures.

15. The method according to claim 1 , wherein the sample is purified by using a purification method selected from the group consisting of centrifugation, size exclusion chromatography, cleaning with solid-phase extraction (SPE) cartridges, dialysis techniques, extraction methods for removing hydrocarbons, filtration, microfiltration, ultrafiltration, nanofiltration, membrane centrifugation and any combinations thereof.

16. The method according to claim 1 , wherein a pH value of the sample is adjusted to a level in a range between pH 3 and pH 8.

17. The method according to claim 1 , wherein the sample is admixed with the silica prior admixing the sample with the reagent comprising a lanthanide(III) ion; or the sample is admixed with the reagent comprising a lanthanide(III) ion prior admixing the sample with the silica; or the sample is admixed with the reagent comprising a lanthanide(III) ion and the silica at the same time.

18. The method according to claim 1 , wherein the sample originates from an oilfield, an oil well, an oil production process, paper manufacturing process, mining industry or water treatment process.

19. The device comprising means for performing the method according to claim 1 for determining concentration of polyelectrolyte or phosphonate in a sample.

20. The method according to claim 1 , wherein the reagent comprising a lanthanide(III) ion is a lanthanide(III) salt or a luminescent lanthanide chelate.