Development and validation of a decigram-scale method for the separation of limonin from limonin glucoside by C-18 flash chromatography

A preparative method for decigram-scale polishing of limonin glucoside (1) with regard to removing traces of limonin (2), the main bitter principle in Citrus, is reported. During the method development and up-scaling stages, sample purity, sample size, solvent amounts, and drying conditions were varied. The resulting polishing method consists of a simple step gradient that utilises food grade solvents, ethanol and water at 15% EtOH and 50% EtOH steps. Using a 75 × 300 mm C-18 column, this method is capable of processing 20 g of material per run in less than 3 h. Recovery of the purified limonin glucoside following evaporation of the solvent was 93.5% (±2.8, n = 6) and the limonin concentrations in the resulting materials were found to be reduced 10- to 15-fold.