Study And Application Of Digital Image Colorimetry Based On Scanner And Smart Phone In Food And Water Sample Analysis

In this thesis,the digital image colorimetric analysis of three anions in food and water sample based on scanner and smart phone was studied.The main steps are as follows:Chapter 1:The concepts,principles,the main influence factors and the application of dispersive liquid-liquid microextraction?DLLME?are reviewed in detail.The digital image colorimetric analysis technology and the commonly used color spaces with different quantitative methods were surveyed.A smartphone based optical platform for colorimetric analysis using a disposable microfluidic technique in agricultural area,biomedical area and analytical chemistry were well reviewed.Chapter 2:A simple and low cost method for perchlorate in various samples based on dispersive liquid-liquid microextraction?DLLME?coupled with digital scanning image analysis was proposed.Orthogonal experiment design was utilized to optimize the amount of extraction solvent and disperser solvent,methylene bluee concentration and buffer pH.Under the optimum conditions,the calibration curve was linear over the range of 10-900?g L^-1?R²>0.9988?of perchlorate.The limit of detection?LOD?and limit of quantitation?LOQ?were 7.9?g·L^-1and 26.5?g·L^-1,respectively.The method was used for the determination of several practical samples and Certified Reference Materials.There was no significant difference with the values of this method and reference.The method has the potential to be made portable for remote test by operating portable scanner and tablet pc.Chapter 3:In acidic solution,nitrite and sulfanilic acid diazo can react to produce a diazo compound,which further combine with naphthyl ethylenediamine hydrochloride and give a purple red azo dye.The red product can be determined with a smartphone colorimeter on the homemade microplate.Under the optimum conditions,the color intensity was proportional to nitrite concentration in2.0-25?g·mL^-1with correlation coefficient 0.9988.The microplate smartphone colorimetric method can be successfully used for the determination of nitrite in food and water samples such as luncheon meat,sausage,pickled vegetable,pickled garlic and ham sausage,etc..Chapter 4:A ternary complex based on catechol violet,copper ion and phenanthroline is established to form a simple chemical sensing system.The system is able to selectively recognize pyrophosphate ion?PPi?in the sample solution due to the existence of PPi,resulting in the distinct color change from green to yellow.The final product extracted by DLLME was sampled on jet-ink printing paper for quantitative analysis.Under the optimum conditions,the intensity of blue channel was proportional to pyrophosphate concentration in 10-90?g·mL^-1.with correlation coefficient 0.9994.The limit of detection?LOD?and limit of quantitation?LOQ?were0.2?g·mL^-1and 0.7?g·mL^-1.The method can be successfully used for the determination of pyrophosphate in tea,beef liver,pork and wheat flour with therecovery range of 97.6%-103.8%.