Raman OH stretching band of water as an internal standard to determine carbonate concentrations

Raman spectroscopy is an efficient method which has been widely employed in many research fields. However, this method is more commonly associated with qualitative study than with quantitative analysis. In this work, a quantitative measurement using Raman spectroscopy is provided. According to the theoretical analysis of Raman intensity, Raman quantitative measurement should be based on the intensity ratio, which can be classified into external and internal standards. This allows the influence from measurement conditions to be eliminated. For aqueous solutions, it is reasonable to treat the Raman OH stretching band of water as an internal standard. In this study, the intensity ratio ICO32−/IW is used to determine carbonate concentrations in solutions, where ICO32− is the intensity of the carbonate band, and IW is the sum of intensities of the two used OH stretching sub-bands.

Research highlights
► Raman quantitative measurement should be based on Raman intensity ratio.
► Water can be treated as an effective internal standard.
► ICO32−/IW is used to determine the carbonate concentrations in solutions.