A single-stop purification for glycine betaine determination in plant extracts by isocratic HPLC

The glycine betaine content of higher plants can be determined by rapid and simple isocratic highperformance Liquid chromatography on a C-18 column. T he method described is particularly suitable for a large number of samples. Starting from a complex dry plant, it consists of a single aqueous extract ion followed by a purification over a sole cationic ion-exchange resin (AG1 , OH-) before simple HPLC quantification. The single-step purification was allowed because the AG1, OH- resin removed 80% of the total amino acids con tained in the extracts. Praline, which interferes with GB HPLC quantificati on, was completely retained by this column. The optimized method for GB qua ntification was then validated by comparison with an IK NMR method.