A new procedure for extraction and measurement of soluble sugars in ligneous plants

An original modification of an analytical procedure has been developed to obtain purified extracts for sugar measurement in different parts of ligneous plants by high‐performance liquid chromatography. Extraction was performed at 4 °C in the presence of water, methanol and chloroform. Only a representative part of the alcohol extract (methanol/water) was purified for analysis. An internal marker such as maltotriose, added during extraction, makes it possible to estimate possible sugar loss and to correct concentrations. Compared with a more standard method based on total soluble sugar extraction, this new method is more precise. The use of internal calibration standards shows good linear progression but does not guarantee good accuracy in the absence of a reference method or plant powder standard. It is a robust procedure which can tolerate experimental variations without affecting the results. The high recovery rate (90%) of maltotriose proves the quality of the procedure and makes it possible to correct sugar concentrations to acceptable limits.