Melamine Assay Methods and Systems

• US 20110207231A1
• Filed: 11/17/2009
• Published: 08/25/2011
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: Sicpa Holding SA
• Original Assignee: Cabot Security Materials Inc. (Sicpa Holding SA)
• Inventors: Doering, William E., Freeman, Richard Griffith, Golightly, Rebecca Stoermer, Natan, Michael J.
• Granted Patent: US 8,574,916 B2
• Time in Patent Office: Days
• US Class Current: 436/98
• CPC Class Codes: G01N 21/658 enhancement Raman, e.g. surface plasmons
• CPC Class Codes: Y10T 436/14 Heterocyclic carbon compound [i.e. , O, S, N, Se, Te, as only ring hetero atom]
• CPC Class Codes: Y10T 436/145555 Hetero-N
• CPC Class Codes: Y10T 436/147777 Plural nitrogen in the same ring [e.g., barbituates, creatinine, etc.]

Abstract

A method of detecting melamine which includes providing a quantity of SERS-active particles and mixing the SERS-active particles with a solution containing melamine. The method further includes detecting a surface enhanced Raman spectrum of the melamine. The foregoing method may optionally include aggregating the SERS-active particles. Aggregation may occur before or after the SERS-active particles are mixed with a solution containing melamine. The method of detecting melamine may optionally include concentration of the SERS-active particles. The method may further include mixing a chaotropic agent having a higher affinity for a selected binding site than melamine into the solution containing melamine. The method may further include mixing a quantity of a SERS-active standard having a known SERS spectrum with the solution containing melamine and SERS-active particles. Assay apparatus and systems are also disclosed.

Claims

1. A method of detecting melamine comprising:

providing a quantity of SERS-active particles;

mixing a solution containing melamine with the SERS-active particles; and

detecting a surface enhanced Raman spectrum of the melamine.

2. The method of detecting melamine of claim 1 further comprising aggregating the SERS-active particles.

3. The method of claim 2 wherein the aggregation step comprises adding an aggregating agent to the mixture of melamine containing solution and SERS-active particles.

4. The method of claim 1 wherein the detecting step is performed without concentration of the SERS-active particles.

5. The method of claim 1 further comprising mixing a chaotropic agent having a higher affinity for a selected binding site than melamine into the solution containing melamine, wherein the chaotropic agent does not exhibit a SERS spectrum.

6. The method of claim 1 further comprising:

providing a quantity of a SERS-active standard having a known SERS spectrum;

mixing the solution containing melamine with the SERS-active particles and the SERS-active standard; and

detecting a surface enhanced Raman spectrum of the SERS-active standard.

7. The method of claim 6 wherein the SERS-active standard is deuterated melamine.

8. A method of detecting melamine comprising:

providing a quantity of SERS-active particles;

providing a quantity of magnetic particles;

associating one or more SERS-active particles with one or more magnetic particles;

mixing a solution containing melamine with the SERS-active particles and magnetic particles;

magnetically concentrating the magnetic particles; and

detecting a surface enhanced Raman spectrum of the melamine.

9. The method of detecting melamine of claim 8 wherein the SERS-active particles are associated with the magnetic particles through electrostatic attraction between the particles.

10. The method of detecting melamine of claim 8 wherein the SERS-active particles are associated with the magnetic particles before the SERS-active particles are associated with the magnetic particles

11. The method of claim 8 further comprising mixing a chaotropic agent having a higher affinity for a selected binding site than melamine into the solution containing melamine, wherein the chaotropic agent does not exhibit a SERS spectrum.

12. The method of claim 8 further comprising:

providing a quantity of a SERS-active standard having a known SERS spectrum;

mixing the solution containing melamine with the SERS-active particles and the SERS-active standard; and

detecting a surface enhanced Raman spectrum of the SERS-active standard.

13. A method of detecting a molecule of interest comprising:

providing a quantity of SERS-active particles;

providing a quantity of a SERS-active standard having a known SERS spectrum;

mixing a solution containing the molecule of interest with the SERS-active particles and the SERS-active standard;

detecting a surface enhanced Raman spectrum of the molecule of interest; and

detecting a surface enhanced Raman spectrum of the SERS-active standard.

14. The method of claim 13 further comprising concentrating the SERS-active particles and the SERS-active standard.

15. The method of claim 14 further comprising:

providing a quantity of magnetic particles;

associating one or more of the SERS-active particles and a select quantity of the SERS-active standard with one or more magnetic particles; and

magnetically concentrating the magnetic particles.

16. The method of claim 13 wherein the SERS-active standard is an analog of the molecule of interest.

17. The method of claim 16 wherein the SERS-active standard is deuterated melamine and the molecule of interest is melamine.

18. An assay system comprising:

a quantity of SERS-active particles;

a quantity of a SERS-active standard;

a container for mixing a solution of a molecule of interest with the SERS-active particles and the SERS-active standard; and

a SERS reader configured to obtain a SERS spectrum of the molecule of interest and a SERS spectrum of the SERS-active standard.

19. The assay system of claim 18 further comprising:

a quantity of magnetic particles; and

a magnetic concentration apparatus.

20. The assay of system of claim 18 further comprising an aggregating agent.

21. The assay of system of claim 18 further comprising a chaotropic agent that does not exhibit a SERS spectrum.

22. The assay of system of claim 18 wherein the molecule of interest is melamine.