Figure 6From: Evaluation and differentiation of the Betulaceae birch bark species and their bioactive triterpene content using analytical FT-vibrational spectroscopy and GC-MSBottom: high wavenumber range of the FT-Raman spectra of the BC1, B(MeOH), BC2 extracts and bark (bottom), compared with the reference spectra of betulin (B), lupeol (L) and betulinic acid (BA), respectively, (top). The arrow indicates the display order. Excitation: 350 mW, 1064 nm.Back to article page