Study On Electrochemical And Fluorescent Analytical Methods Of Food Antioxidants TBHQ And PG

TBHQ and PG are commonly used synthetic antioxidants,often used in cooking oil,oil products,which can protect the cooking oil and its products from oxidative damage and deterioration,but unreasonable use will be harmful to human health.Therefore,developing effective,sensitive and rapid antioxidant detection technology is of great significance to ensure food safety,protect the public’s health and guarantee people’s life safety.In recent years,due to its advantages of high sensitivity,good selectivity,short response time and easy-portability,electrochemical and fluorescence sensing is widely used in the detection of food ingredients,food additives,heavy metals and pesticide residues,etc.This study takes the application of nanomaterial-based electrochemical and fluorescent sensors in the field of food testing as the background.This work combines the advantages of carbon nanotube with the advantages of electrochemical sensor,realizing the rapid determination of organophosphorus pesticide residues and catechol respectively.The main research and conclusions are as follows:1.Under the electrocatalysis of TBHQ,reversible redox reactions can occur and this reaction will produce electrochemical signals.Based on this phenomenon,herein,we developed a green and cost-effective electrochemical method for TBHQ detection in edible oils.This electrochemical sensor was constructed by an in-situ surface electrochemical co-reduction method using the mixture of graphene oxide（GO）and HAuCl₄ coating on the surface of electrode as a precursor.GO was in situ electrochemically reduced to ERGO on the surface of electrode,accompanied by the simultaneous formation of AuNPs,which results in the fabrication of a conductive network of amorphous AuNPs/ERGO binary nanocomposite.Significantly,the resulting AuNPs/ERGO binary nanocomposite combines the advantages of AuNPs and ERGO,which exhibits an excellent performance towards simultaneous determination of TBHQ and BHA,allowing sensitive detection of TBHQ and BHA in the wide linear ranges of 0.1⁷μg mL^-1 and 0.1¹0μg mL^-11 with low detection limits of 0.0503μg mL^-11 and 0.0419μg mL^-1,respectively.The practicability of this electrochemical sensing platform was realized in simultaneous detection of BHA and TBHQ in edible oil samples.The results indicate that the constructed electrochemical sensing platform presents satisfactory linear range,low detection limit,good accuracy and reproducibility.More importantly,the facile and environment-friendly surface electrochemical co-reduction strategy provided here maybe open a cost-effective way for setting up a binary nanocomposite or polynary nanohybrid-based electrochemical sensing platform,which benefits for extending the application of electrochemical sensor for the green,facile and sensitive analysis of electroactive compounds in food samples.2.Aiming to improve the selectivity of electrochemical detection of TBHQ,we combined high sensitivity of electrochemical detection technology with good specificity of molecular imprinting technique to construct molecularly imprinted sensor.At first,PdAuNPs-ERGO nanocomposite modified electrode was prepared by electrochemical co-reduction method.Afterwards,the electrochemical sensor based on molecularly imprinted technology was constructed by in-situ electrochemical polymerization of TBHQ imprinted membranes on the surface of modified glassy carbon electrode（GCE）using o-phenylenediamine（oPD）as functional monomer and then eluted by cyclic voltammetry.Notably,the constructed sensor which combines the advantages of nanotechnology,electrochemical technology and molecular imprinting technology exhibits outstanding performance and allows sensitive detection in the linear range of 0.5-60μg mL^-1（ppm）with low limits of detection of 0.046μg mL^-1.The constructed sensor is achieved by detecting TBHQ in oil samples to confirm its feasibility,showing good accuracy and reproducibility.which provides a novel and effective approach for TBHQ detection in food samples.3.By utilizing the competitive interaction between the photo-induced electron transfer effect of carbon dots（CDs）/Fe（Ⅲ）ions and the complexation reaction of TBHQ/Fe（Ⅲ）ions,herein,a simple and rapid fluorescent switchable methodology was developed for high selective and sensitive determination of TBHQ This novel fluorescent switchable sensing platform allows determining TBHQ in a wider range from 0.5 to 80μg mL^-1 with a low detection limit of 0.01μg mL^-1.Furthermore,high specificity and good accuracy with recoveries ranging from 94.29 to 105.82%in spiked edible oil samples are obtained with the present method,confirming its applicability for the trace detection of TBHQ in complex food matrix.Thus,the present method provides a novel and effective fluorescent approach for rapid and specific screening of TBHQ in common products,which is beneficial for monitoring and reducing the risk of TBHQ overuse during food storage.4.In this work,a novel indirect fluorescence quenching method is firstly proposed to sensitively and selectively determine propyl gallate（PG）,by the specificity of organic molybdate complex（OMC）reaction between MoO₄^2-and PG to successfully quench the fluorescence of graphitic carbon nitride nanosheets（g-C₃N₄）nanosheets.On the basis of the novel phenomenon,a universal sensing strategy is proposed to design fluorescence detection method for analyzing the content of PG.The developed indirect fluorescence sensor allows highly sensitive detection of PG in a wide range from 0.5 to 200μg mL^-1 with a low detection limit of 0.11μg mL^-1,excellent anti-interference properties and short assay time.Further,the analytical results obtained by fluorescence sensor were consistent with the results gained by high-performance liquid chromatography（HPLC）,demonstrating the new design is applicable for sensitive detection of PG in real samples with satisfactory results.The present method provides a novel and effective fluorescent approach to monitor excessive use of PG and offers a rapid,sensitive and selective detection technology for food quality control.