Research On The Basic Fluorescence Properties And Application Of Lac Red Pigment And Cochineal Red Pigment

Lac dye and cochineal dye both are natural pigments derived from insects,the laccaic acid A is the main ingredient of the lac dye,the carminic acid is the main ingredient of the cochineal dye.Laccaic acid A and carminic acid are all anthraquinone and have fluorescent properties.This paper systematically studied their basic fluorescent properties and their application in fluorescence analysis,the paper aims to deepen the basic research on laccaic acid A and carminic acid,and lay the foundation for the development of their application as fluorescent probes in the fields of chemistry,environment and biology,and the application prospects of lac dye and cochineal dye are expected.The research content of this paper is mainly composed of four parts.?1?The basic properties and influencing factors of the fluorescence and absorption spectra of lacquer acid A were researched,and its recognition of metal ions and its application in practical detection were explored.It was found that Cu²⁺,Fe³⁺,Fe²⁺and Pb²⁺quenched the fluorescence of laccaic acid A,while Zn²⁺and Al³⁺enhanced the fluorescence,and Al³⁺showed the specificity of enhancing the fluorescence intensity of laccaic acid A.Other metal ions has little effect on the fluorescence intensity.In the presence of Al³⁺?0.04 mol/L?,the fluorescence intensity of the laccaic acid A has a good linear relationship with its concentration.By detecting the content of laccaic acid A added in two different beverages,the results showed that the sample recover y ranged from 95.0 and 109.3%,and the relative standard deviation?RSD?is 1.9%⁵.4%.In this experiment,a new method for detecting laccaic acid A was developed,which has practical application value.?2?The fluorescence properties and influencing factors of carminic acid were researched,and its recognition of metal ions and its application in actual detection were explored.It was found that Al³⁺greatly enhanced the fluorescence intensity in different solvent systems.A method for detecting Al³⁺in water samples using carminic acid as a fluorescent probe was developed.The quantitative combination of CA and Al³⁺was firstly used as a fluorescent probe to detect Fe³⁺in water samples.In addition,a fluorescence analysis method for detecting the content of carminic acid in the sample is established.The preliminary application experiment results show that the fluorescence analysis method can effectively detect Al³⁺and Fe³⁺in water,and the results are accurate and reliable.In addition,the content of carminic acid added in water or fruit beverage is detected by fluorescence method,and the sample recovery rate is 92.9%¹17.5%,the relative standard deviation is 1.9%⁵.8%.In summary,this study provides an application method for exploring the rapid detection of the content of carminic acid,Al³⁺and Fe³⁺in water or juice beverages.?3?The CA/CD inclusion complex was prepared and the changes in fluorescence properties before and after inclusion were investigated.It was found that?-cyclodextrin can increase the fluorescence intensity of carminic acid by about 2times.The inclusion complexes were characterized by FT-IR,NMR,SEM and TG.It is speculated that the possible inclusion mode is that the benzene ring linking the methyl group and the group above it may be in the van der Waals force,hydrogen bond from the narrow side of the?cyclodextrin into the interior of the cavity.?4?The carbon quantum dots?ld-CQDs?were prepared by alcohol calorimetry,and their structures and fluorescence properties were studied.The study found that in the ethanol system,when Ex is 480 nm,the concentration of ld-CQDs is 0.1 mg/mL,the fluorescence is the strongest,the quantum yield is 0.4,and the fluorescence of the lac dye is about 7 times stronger.The loading of ld-CQDs on the surface of silica gel significantly enhances the fluorescence intensity of si lica gel,and the fluorescence can change with the excitation wavelength,indicating that ld-CQDs can be used as a fluorescent tracer for silica gel materials.Through preliminary applicati on research,it was found that ld-CQDs can be used for accurate and reliable determination of ethanol content in commercial wines.