Quantitation of 4-O-methylglucuronic acid from plant cell walls

► The 4-O-methyl-α-d-glucopyranosyl uronic acid (meGlcA) was purified from commercial birch xylan. ► meGlcA content was underestimated if glucopyranosyl uronic acid (GlcA) was used as calibration standard in GC or HPAEC-PAD. ► A method for better estimation of meGlcA content derived from acid methanolysis and GC analysis is suggested.