Research Of Migration Behavior And Detection Of Fluorescent Brightener By Different Lateral Irradiation On Paper-based Analytical Device

Paper-based analytical device(PAD)has great merit of price moderate,simplicity and portability,ease of processing,environmentally friendly,suitable for real-time detection on site,economical in the use of reagent and good for selection.Which was widely used in environmental detection,diagnosis of symptoms in early period,monitoring progression,evaluating prognosis and food quality control,et al.However,low sensitivity was a obstacle that limits the widespread application of paper chip.Therefore,it’s very important to introduce of the electrokinetic stacking(ES)into the paper channel for improving the detection sensitivity of low abundance target analytes.In the first chapter of this work,we mainly have a brief descriiption of PAD.Detailedness presentation of the fabrication method,the enrichment means and detection way of the paper microfluidic channel.Moreover,the present research status of colorimetric and fluorometric in PAD was emphasized.In addition,has a briefly description of food contact materials(FCMs)and its mirgration regularity.In the second chapter,the quantitative performance of PAD ES was investigated,and a simple and rapid method for real-time verification of fluorescent whitening agent 85(VBL)was proposed.Firstly,we changed the optical stucture of excitation beam path for LED-induced fluorescence from ipsilateral reflexion to different lateral irradiation,making the stucture more tightly,operating more conveniently and protecting the observer’s eyes.Secondly,with FAS the analyte of VBL stacked as a bule band,which excited by ultraviolet light emitting diode(UVLED)to visualize for analyzing.The fluorescence image capturedic via smartphone,and processed by Image J.Established curve graph of fluorescence intesity varied with the concentration of VBL,without the aid of instrument can be quantitative analysis of fluorescent agents rapidly.The experimental conditions such as the area of light window for detection,the concentration of background electrolyte(BGE)and LED wattage were optimized,respectively.Under the optimum conditions,the quantitative performance and enrichment effect of this established method were disscussed.The limit of detection(LOD)of VBL was 10 ng/mL and the sensitivity of this portable PAD system was 51 folds enhanced by ES.Applied the system to measure the total amount of fluorescer in food container and facial mask essence,and validate by spiked recovery.It shows that PAD has the potential of quick and easy for verification.This method has various advantages of the paper chip when compared with other instrument analysis methods(inverted fluorescence microscope and so on).Furthermore,the highly sensitivity of this system lay the foundation of montoring low-abundance biomarker.In the third chapter,an easy and effective means used sucessfully for determination of the migratory behavior of optical whitenels without smple pretreatment was proposed.A piece of paper whose size was 5 mm×3 mm containing target component of VBL was loaded directly onto paper strip whose size of 35 mm×4 mm,so that VBL migrated out of the positive sample and accumulated for rapidly fluorometric assay.The conditions affecting the mobility of VBL such as stacking time,fixed volume,adsorption matrial,applied voltage,concentration of BGE and electroosmotic flow(EOF),pH of the cathode solution and so forth were discussed.The LOD of VBL was 2.3 ng.On this basis,the migration amount of fluorescer in napkin was analyzed immediately.This work loading sample directly for analysing,and can be used for monitoring hazardous substances in the food packing materials in real time to provide criterion of its dosage.