Comparison of two liquid-state NMR methods for the determination of saccharides in carrot (Daucus carota L.) roots.

In order to determine the saccharide content of plant tissues, we studied a new non-destructive and fast analytical method that we call "direct quantitative proton nuclear magnetic resonance spectroscopy" (d q (1)H NMR): the application of quantitative proton nuclear magnetic resonance spectroscopy (q (1)H NMR) to non modified plant tissues along with capillary tubes containing a reference compound (for quantification) and deuterium oxide (for locking). Using this method, the saccharide content of samples of carrot (Daucus carota L.) roots was compared to the results given from similar samples by the formerly published q (1)H NMR determination of extracts obtained by the O'Donoghue/Davis method. The content in glucose and sucrose is significantly higher with the direct method than when an extraction step is included; the content in fructose is not significantly different. If a possible detection of saccharides included in glycosylated biological compounds is to be excluded, a more complete extraction of saccharides is probably obtained using the direct method.