Purification of crude Ioversol using continuous deionization

A method for the purification of a 5-amino-N,N'-bis-(2,3-dihydroxypropyl)-2,4,6-triiosoidophthalamide production waste stream comprising the steps of:

• a) passing said crude 5-amino-N,N'-bis-(2,3-dihydroxypropyl)-2,4,6-triiodoisophthalamide production waste stream through a mixed-resin bed contained between a catoin permeable membrane which allows the passage of cations and not anions and an anion permeable membrane which allows the passage of anions and not cations;
• and
• b) applying an electrical current to said cation and anion permeable membranes;
• whereby impurities are pumped through said cation and anion permeable membranes to purify said 5-amino-N,N'-bis-(2,3-dihydroxypropyl)-2,4,6-triidoisophthalamide production waste stream.

A method for the purification of a crude intermediate of Ioversol comprising the steps of:

• a) passing said crude intermediate of Ioversol through a mixed-resin bed contained between a cation permeable membrane which allows the passage of cation sand not anions and an anion permeable membrane which allows the passage of anions and not cations;
• and
• b) applying an electrical current to said cation and anion permeable membraens;
• whereby impurities are pumped through said cation and anion permeable membraens to purify said crude intermediate of Ioversol.