Preparation Of Molecularly Imprinted Polymers And Their Application To The Detection Of Domoic Acid In Shellfish

Domoic acid?DA?is a kind of amnesic shellfish poisons with high toxicity that can be easily bio-accumulated in shellfish animals through the foodchain,which can cause memory loss,coma and possibly death.At present,there is no specific antidote for it.The conventional analytical techniques for the detection of DA include HPLC,HPLC-MS and so on.However,due to the high complexity of the sample matrix and interference factors,sophisticated and time-consuming sample preparation procedures are required.Molecularly imprinted polymer?MIPs?is a kind of high polymer materials with strong organic solvent,acid and alkali resistance,which has the ability to recognize and bind specific target molecules.In this paper,the MIPs of DA was prepared through two different methods,including emulsion polymerization and precipitation polymerization.Then,the as-prepared DA-MIPs was used in the sample preparation of DA detection from shellfish.The specific content is as follows:?1?The DA-MIPs was prepared by emulsion polymerization using1,3,5-pentanetricarboxylic acid?PTA,a structural analog of DA?as the template molecule,4-vinyl pyridine?4-VP?as the functional monomer,ethylene glycol dimethacrylate?EGDMA?as the crosslinker,azobis?isobutyronitrile??AIBN?as the initiator and Span80/tween80 as the composite emulsifiers.The results indicated that using 0.25 mmol PTA,1 mmol 4-VP,7.5 mmol EGDMA and 80 mg AIBN with the water bath at the temperature of 60^oC,stirring speed of 600rpm and the synthesis time of 18 hours,the obtained MIPs have the best absorption ability and the imprinting factor was 2.1.Scanning electron microscope?SEM?images show that the MIPs with an average diameter about 180 nm.The results of adsorption isothermal curve and scatchard analysis show that the MIPs had the maximum absorption amount about 1294.4?g g^-1,taking about 30 min to attain absorption equilibrium.The dissociation constant was 13.53 mg L^-1.The prepared MIPs were used as adsorbents for the rapid detection of DA in shellfish samples combined with HPLC.The recoveries of DA ranged from 93.0 to 98.7%with RSD in the range of 2.2⁵.2%.When the adsorption materials were used repeatedly 5 times,the adsorption efficiency for DA also reached 95.1%.Thus,the prepared MIPs could be successfully applied to the sample pretreatment for separation and enrichment of DA in spiked shellfish samples.?2?The Magnetic molecularly imprinted polymer?MMIPs?of DA was prepared by precipitation polymerization method using PTA and oleic acid modified Fe₃O₄ as template and magnetic nuclei,respectively.In order to obtain the best absorption ability,optimal synthesis conditions were as follows:50 mg of Fe₃O₄,the molar ratio of PTA,4-VP and EGDMA was1:6:20,20 mL of DMF as solvent and 0.1 g of AIBN as initiator,water bath at the temperature of60^oC and the synthesis time of 12 hours.The imprinting factor was 1.9.SEM images show that the MMIPs with diameter about 350 nm.The results of adsorption isothermal curve and scatchard analysis show that the MMIPs and MNIPs had the maximum absorption amount about1418.4?g g^-11 and 695.3?g g^-1,respectively,taking about 20 min to attain absorption equilibrium.The dissociation constant of MMIPs and MNIPs was 12.21 mg L^-1 and 10.94 mg L^-1,respectively.The saturation magnetization of the MMIPs was 10.1 emu g^-1.The prepared MMIPs were used as adsorbents for the rapid detection of DA in shellfish samples combined with HPLC.The recoveries of DA ranged from 80.5 to 92.1%with RSD in the range of 2.7%⁹.2%.When the adsorption materials were used repeatedly 5 times,the adsorption efficiency for DA also reached 90%.Thus,the prepared MMIPs could be successfully applied to the sample pretreatment for separation and enrichment of DA in spiked fish samples.In conclusion,the DA-MIPs and DA-MMIPs were synthesized through molecular imprinting technique,both of them presented high specificity and selectivity adsorption of DA in solutions.The MMIPs with magnetic could be used to efficiency and separate DA in shellfish samples pretreatment to assure the method of detecting DA was accurate and rapid..