Process for the ultrapurification of alginates

Abstract

A method for obtaining solutions of non-structurally modified salts of alginate, with endotoxin content less than 20 EU/g includes obtaining an alginate solution having a concentration ranging from 1.6 to 2.0% by weight by adding commercial grade alginate powder to a saline solution. The alginate solution obtained is filtered on at least one hydrophilic filter, and a filtered alginate solution is recovered. The filtered alginate solution obtained is further filtered on a charge-modified hydrophobic filter, and an alginate solution having an endotoxin content less than 20 EU/g is recovered.

1 . A method for obtaining solutions of non-structurally modified salts of alginate, with endotoxin content less than 20 EU/g, comprising:
 a. obtaining an alginate solution having a concentration ranging from 1.6 to 2.0% by weight by adding commercial grade alginate powder to a saline solution while controlling pH;   b. filtering the alginate solution obtained from step a) on at least one hydrophilic filter and recovering a filtered alginate solution; and   c. filtering the filtered alginate solution obtained from step b) on a charge-modified hydrophobic filter and recovering an alginate solution having an endotoxin content less than 20 EU/g.   
     
     
         2 . The method according to  claim 1 , wherein said alginate powder is sodium alginate powder. 
     
     
         3 . The method according to  claim 1 , wherein said alginate has a composition comprising 52.26% M and 47.74% G, corresponding to an M/G ratio of 1.093. 
     
     
         4 . The method according to  claim 1 , wherein said step of filtering on at least one hydrophilic filter is carried out on three hydrophil filters of cellulose acetate hydrophils. 
     
     
         5 . The method according to  claim 5 , wherein the first one of said three filters has a pharmaceutical grade 30 and a nominal pore size of 2 μm, the second one of said three filters has a pharmaceutical grade 60 and a nominal pore size of 2 μm and the third one of said three filters has a pharmaceutical grade 90 and a nominal pore size of 2 μm. 
     
     
         6 . The method according to  claim 1 , wherein said hydrophobic filter is a charge-modified Nylon filter. 
     
     
         7 . The method according to  claim 7 , wherein said hydrophobic filter is a Nylon 66 filter having a positive electric charge. 
     
     
         8 . The method according to  claim 1 , wherein the saline solution of alginate includes sodium alginate. 
     
     
         9 . The method according to  claim 8 , wherein the sodium alginate is employed for parenteral use in human transplants. 
     
     
         10 . The method according to  claim 9 , wherein the sodium alginate is formed into alginate/polyornithine microcapsules to be used in human cell transplants.