Measuring concentration of analytes in liquid samples using surface-enhanced Raman spectroscopy

A method of measuring the amount of an analyte in water, the method comprising the steps of:

• obtaining a sample of water of known volume containing an analyte;
• mixing a known amount of an isotopologue with the sample;
• mixing Raman-scattering nanoparticles with the sample;
• wherein the analyte is a molecular cation and comprising adding an anionic compounds to the mixture.

A method of measuring the amount of an analyte in water, the method comprising the steps of:

• obtaining a sample of containing an analyte;
• reacting the analyte with a known initial amount of a compound so as to leave a remaining amount of the compound unreacted;
• mixing a known amount of an isotopologue of the compound with the unreacted compound;
• mixing Raman-scattering nanoparticles with the isotopologue and the unreacted compound;
• producing a Raman spectrum of the mixture;
• and,
• performing a ratiometric analysis of peaks or bands within the Raman spectrum corresponding to the compound and the isotopologue within the Raman spectrum to quantify the analyte.