Analysis Of Food Additives By Portable Capacitive Sensors Based On Molecular Imprinting

Food additives are an important part of modern food industry,which play an important role in improving food flavor and prolonging food shelf life.However,excessive additives can easily aggravate asthma,migraine and even induce cancer.Traditional analytical methods,such as chromatography and spectroscopy,are limited to some extent because of high cost,complex operation and long detection time.Therefore,it is necessary to develop a simple,rapid,accurate and effective method for the detection of food additives.In recent years,molecularly imprinted capacitive sensors have attracted extensive attention in the field of food additive analysis due to their advantages of simple operation,good stability and high sensitivity.Molecularly imprinted polymer(MIP)is an excellent material for selective adsorption and specific recognition.The specific array of "molecular capacitors" based on molecular imprinting enables the novel capacitive sensor with MIP as dielectric layer to generate significant electrochemical signals,achieving rapid and accurate detection of target substances.In this paper,a variety of chromatographic column capacitive sensors were constructed based on strong,weak and non-electrolyte imprinted polymers for the detection of food additives.The main contents are as follows:Part One Analysis of strong electrolyte food additives by molecularly imprinted portable capacitive sensorsChromatographic column capacitive sensors were designed by freezing polymerization of sunset yellow and sodium cyclamate as the template of molecularly imprinted polymers.In the experiment,the molecularly imprinted polymers were prepared with N,N-methylenebisacrylamide as crosslinking agent,dimethyl diallyl ammonium chloride as functional monomer,sodium hydrogen sulfite and ammonium peroxydisulfate as initiator.Molecularly imprinted capacitive sensors were constructed by axially winding two polyimide covered copper wires using a conical plastic pipette as the container of molecularly imprinted polymer.Under optimal conditions,the linear ranges of sunset yellow and sodium cyclamate were 8.60×10-10-3.11×104 mg and 9.10×10-10-5.61×104 mg,and the detection limits were 4.79×10-10 mg and 2.63×10-10 mg respectively.Experiments show that the molecularly imprinted capacitive sensors have high sensitivity,stability and selectivity,and can be applied to the detection of sunset yellow and sodium cyclamate in real samples.Part Two Analysis of weak electrolyte food additives by molecularly imprinted portable capacitive sensorsNovel chromatographic column capacitive sensors based on molecularly imprinted polymers were designed by using weak electrolyte benzoic acid and citric acid as templates,N,N-methylenebisacrylamide as crosslinking agent and diallylamine as functional monomer Under optimal conditions,the molecularly imprinted capacitive sensors showed linear ranges of benzoic acid and.citric acid are 5.50×10-11-3.56×10-5 mg and 3.40×10-10-1.12×10-3 mg respectively.The detection limits were 3.24×10-11 mg and 1.34×10-10 mg respectively.The method with good sensitivity,stability,selectivity and reproducibility in real sample analysis showed promising applications of the molecularly imprinted capacitive sensors in the fields of food additives.Part Three Analysis of non-electrolyte food additives by molecularly imprinted portable capacitive sensorsUnique portable capacitive sensors were designed and fabricated by using non-electrolyte as templates.In the experiment,non-electrolyte glyceryl monostearate and glucose were used as template molecules,and diallylamine and 3-(acrylamido)phenylboronic acid were respectively used as functional monomers to prepare molecularly imprinted polymers.Novel molecularly imprinted capacitive sensors were prepared by winding copper wires in a planar spiral mode and using MIP as dielectric layers.Under optimal experimental conditions,the linear ranges of glyceryl monostearate and glucose were 2.35×10-8-6.56×10-3 mg and 2.10×10-9-3.50×10-3 mg respectively,and the detection limits were 3.71×10-9 mg and 6.94×10-10 mg respectively.Experimental results show that the molecularly imprinted capacitive sensors can be applied to the analysis of real samples.