Patent ID: 8445671

Claim:
A method for preparing polyanhydroglucuronic acid salts comprising the steps of: hydrolysis of a polyanhydroglucuronic acid-containing material in the presence of an inorganic and/or organic salt or base to form a homogenous solution comprising a fully hydrolysed salt of polyanhydroglucuronic acid; and subsequently subjecting the homogenous solution formed by the hydrolysis step to ion exchange in the presence of one or more water soluble and/or partially soluble inorganic and/or organic salt or base with a different cation from the inorganic and/or organic salt or base used in the hydrolysis step to form a binary or higher salt of polyanhydroglucuronic acid, the method being carried out at a temperature of from 15° C. to 30° C.; wherein the hydrolysis is carried out in an aqueous solution; wherein the inorganic and/or organic salt and/or base used in the hydrolysis step is selected from the group consisting of any one or more of chlorides, sulphates, carbonates, formates, acetates or alkali and/or alkaline earth metals, hydroxides of alkali and/or alkaline earth metals, alkylamines and alkanolamines, in concentrations ranging from 0.001 to 5 mol/1; wherein the water soluable and/or partially soluble inorganic and/or organic salt and/or base used in the ion exchange step is selected from the group consisting of any one or more of hydroxides, chlorides, nitrates, borates, sulphides, sulphates and acetates; wherein hydrolysis is carried out for a period of from 15 to 30 minutes; and wherein ion exchange is carried out for a period of from 15 to 30 minutes.