Preliminary Study On The Effect Of Chitonsan Oligosaccharide Derivatives On Cadmium Content In Scapharca Subcrenata

Nowadays, heavy metal pollution has become an important issue that threats thesafety of aquatic products. As common bivalves, Scapharca subcrenata has a strongability to accumulate heavy metals and can`t exclude by itself, so it has become a se-rious potential danger to food safety.Carboxymethyl chitosan oligosaccharide (CM-COS) is the production of car-boxymethylation to COS, the introduction of carboxymethyl (-CH2COOH) enhancedits water solubility and ability to combine metal ions. This paper investigates thepreparation conditions of CM-COS and researches the coordination conditions ofCM-COS to magnesium ion, both the CM-COS and CM-COS-Mg complex are usedto remove the Cd from Scapharca subcrenata.The results showed that: both the mass addition of NaOH and chloroacetic acid(CA), the concentration of NaOH has significant impact on substitute degree (D.S.) ofCM-COS. When the mass ratio of NaOH and COS is4:1,NaOH`s mass concentrationis40%, and and molar ratio of CA with chitosan oligosaccharide units (glucosamine)is1:1, the D.S. of production is the highest, up to1.05; Temperature, pH, D.S. has asignificant impact on the adsorption of magnesium ion, and the influence order wereD.S.> pH> temperature> addition of magnesium ion. Optimum adsorption conditionsis the temperature of system reaction20℃, pH9, D.S.0.89, molar ratio of magne-sium ion and sugar is0.5. It was found that the CM-COS(1000Da,DS0.50) can effec-tively remove the Cd in vivo of Scapharca subcrenata. After the Scapharca subcre-nata were treated with CM-COS at the dosage of50mg/L seawater, the content of Cdcan be deduced by36.5%in three days.