COMPARISON OF CATION-EXCHANGE AND CHELATING CATION-EXCHANGE RESINS FOR THE CONCENTRATION OF SAXITOXIN

Current methods for the concentration of paralytic shellfish poisons involve passage of an extract solution through a column of cation-exchange resin, followed by elution and subsequent passage through a column of size-exclusion medium. Although effective, such procedures are tedious and time consuming. The results of a study comparing the characteristics of a cation-exchange resin with a chelating cation-exchange resin indicate that the latter is selective towards saxitoxin (the most important and most studied of the toxins). In addition, the chelating cation-exchange resin has faster kinetics for abstraction of saxitoxin from solution than does the cation-exchange resin. These features recommend chelating cation exchange for the initial separation of saxitoxin followed by concentration and separation of additional toxins by the normal procedure.