A process for preparing a composition comprising the compound glucosamine sulfate metal chloride, wherein the metal is selected from the group consisting of potassium, sodium, magnesium, lithium, calcium, zinc and manganese, said compound having a purity level of at least about 97%, which comprises the steps of:
- (a) contacting glucosamine hydrochloride with a hydroxide of said metal in the presence of water to form an aqueous solution of glucosamine free base and the chloride of said metal;
- (b) acidifying the aqueous solution resulting from step (a) with sulfuric acid to form an aqueous solution of glucosamine sulfate and the chloride of said metal;
- and
- (c) recovering the compound by freeze-drying the solution from step (b) at a temperature and at a reduced pressure for such period of time that:
- (i) at least about 90 wt. % of the water is removed and (ii) decomposition of the compound glucosamine sulfate metal chloride is limited to a maximum of about 3%.