Robust quantitative SERS analysis with Relative Raman scattering intensities.

Robust quantitative analysis methods are very attractive but challenging with surface-enhanced Raman scattering (SERS) technique till now. Quantitative analysis methods using absolute Raman scattering intensities tend to desire very critical reproducibility of SERS substrates and consistency of testing conditions, as batch differences and inhomogeneity of SERS substrates as well as the fluctuation of measuring parameters placed challenging obstacles. Relative Raman scattering intensities, on the other hand, can release the adverse interferences mentioned above and provide effective and robust information as it is independent of the reproducibility of SERS substrates. By establishing external calibration working curves, we achieved accurate molecule composition prediction of molecules in multi-component systems. Further, by choosing or adding a label molecule with known concentration as Raman internal standards, the concentration of target molecules can be easily predicted. This approach proved the effectiveness and robustness of quantitative analysis with the relative Raman scattering intensities, even carried out with a flexible inhomogeneous SERS substrate.