Analysis of metabolites in aqueous solutions by using laser Raman spectroscopy.

Laser Raman scattering is conducted on aqueous solutions that contain organic chemicals that include glucose, lactate, ascorbate, pyruvate, and urea. At the concentrations of interest (below 1.0 wt. %), these various metabolites are found to scatter light independently of each other, and the scattering is linearly proportional to their concentrations. Through proper subtraction of water background scattering, the spectrum that is due to metabolite scattering is obtained and the composition of the solution can be determined by fitting its Raman spectrum with a linear sum of the known pure metabolite spectra. The spectrum of rabbit aqueous humor is presented and the potential application of this analytical method, such as noninvasive glucose monitoring, is discussed.