Adaptation of the Carrez procedure for the purification of ferulic and p-coumaric acids released from lignocellulosic biomass prior to LC/MS analysis

The objective of this study was to adapt and improve an environmentally friendly and fast routine method for the analysis of ferulic and p-coumaric acids released from grass cell-walls by alkaline hydrolysis. This methodological development was performed on maize samples selected for their contrasted contents in ferulic and p-coumaric acids as a consequence of their different maturity stages (from stage of 7th leaf with visible ligule to stage of silage harvest). We demonstrate that the Carrez method is an efficient substitute to the common solvent-consuming extraction by ethyl acetate for the preparation of samples suitable for HPLC–ESI-MS analysis. We prove that it is possible to replace methanol by ethanol in the Carrez step and at last we propose a scale reduction of this procedure that offer a first step towards high throughput determinations. The new method leads to a solvent consumption reduced by a factor 100 and only requires ethanol as organic solvent.