Preparation, Properties And Application Of Malachite Green Molecularly Imprinted Membrane

Malachite green(MG)is a toxic tripHenylmethane compound,the metabolite in aquatic organisms is leucomalachite green(LMG),which is more toxic than MG.MG has good effect on prevention and treatment the diseases of aquatic products and low cost.In recent years,the problem which the residues of malachite green has been exposed repeatedly,caused a serious threat to human health and aquatic products trade,so many countries have issued a ban for malachite green and prohibit its use in any edible animals.In this study,malachite green-molecularly imprinted membranes(MG-MIMs)are synthesized using surface molecular-imprinting,and using glass fiber membranes as the substrate and target structure analogues as the template substitute.Which not only solved the problems that the "template leakage" of traditional molecular imprinting method and the imprinting site "embedding" deeply,but also combined the molecular imprinting technique with the membrane separation technology,which make the recognition sites located on the surface of the polymer and accelerated the mass transfer rate of MG-MIMS.First of all,the synthesis conditions of MG-MIMs were optimized in this study,and finally we choosed hydropHobic glass fiber membranes as polymerization substrates,methyl violet(MV)as template substitute,4-vinylbenzoic acid as functional monomer,ethylene glycol dimethacrylate(EGDMA)as crosslinking agent,azobisisobutyronitrile(AIBN)as initiator and acetonitrile(ACN)as solvent,with the molar ratio of template substitute: functional monomer: crosslinking agent as 1: 4: 24 to prepare MG-MIMs.The mic-morpHology,adsorption capacities,molecular structure and thermal stability of MG-MIMs were investigated by scanning electron microscopy(SEM),specific surface mount(BET),ultraviolet visible spectropHotometer(UV-VIS),fourier transform infrared spectroscopy(FT-IR)and simultaneous thermal analyzer(TGA/DSC).The results showed that most functional monomers had cross-linked with the crosslinking agents,the surface of MG-MIMs was fluffy,multihole and loosened,and MG-MIMs had good thermal stability in the using temperature range.Secondly,the extraction conditions of MG-MIMs were optimized.The results revealed that the optimal extraction conditions were as follows: 30mL20% acetonitrile/PBS buffer solution(V%,pH = 5,salt concentration = 1%)as extraction solvent,oscillated at the oscillation rate of60times per minute for20min,and then1 mL10% acetic acid/acetonitrile(V%)solution was used to elution targets.Under the optimal preparation and extraction conditions,the adsorption properties of MG-MIMs were investigated,the results indicated that MG-MIMs could reach adsorption equilibrium at20min,and the saturated adsorption to MG and LMG were 24.25ngcm-2and13.40ng·cm-2,and the maximum imprinting factors were2.41and3.20 respectively.At the same time,MG-MIMs have better performance of acid,alkali and organic solvents resistance,when use5times repeatedly,the specific recognition ability to the targets is good and the adsorption capacity is basically stable.Finally,the methodology was evaluated in this study and the results revealed that the linear range of MG and LMG was0-50?gL-1,and the linear correlation coefficient was more than 0.9991.The recovery rate of blank fish and shrimp were72.31%-93.26%and79.53%-96.26%,RSD were0.78%-2.33% and0.73%-3.72%,respectively,and limits of detection(n = 3)of MG and LMG were0.005?gkg-1and0.02 ?g·kg-1,the limits of quantification(n = 10)were0.02 ?g·kg-1and0.05?gkg-1,respectively.The results show that all the indexes meet the demand of the quality control of malachite green residues analysis.Combining molecular imprinting with rapid detection techniques,and the limit of detection is1?g·kg-1,which meet the national standard for MG,and suitable for analyzing real samples.In this study,we combined molecular imprinting technology with rapid detection technology,and taked advantage of special binding sites which on the surface of molecular imprinted polymers,greatly shorten the sample pretreatment time.It has the advantages of simple,fast,matrix interference resistance and high selectivity,which can effectively improves the test results inaccurate of the existing rapid detection technology caused by the lack of proper preparation techniques.It is expected to be combined with the rapid detection technology,and to provide a new method for detection of trace MG in complex matrices.Thus,the research has the certain theory significance and practical significance.