Evaporative Light Scattering Detection In Food Safety And Its Coupling With Presurized Capillary Electrochromatography

Evaporative light scattering detection (ELSD) as a common detection, with the advantage of not to be limited by the substance structure, is suitable for analysis of most volatile and semi-volatile materials. The detection is commonLy used in the area of natural product, medicine, pesticide residues and food satety and analysis. With the rapid development of analysis of natural product, medicine and food safety, ELSD will become more popular.This thesis is divided into five parts as follows:The first chapter briefly introduced the background and significance of the thesis, including the theory and application of ELSD, the significance of the research of pressurized capillary electrochromatography- evaporative light-scattering detector (pCEC-ELSD), current application and analytical method of food additives.In the second chapter, a high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD) which was used in the determination of food safety, has been developed for the simultaneous determination of five synthetic sweeteners (acesulfame-K, saccharin sodium, sodium cyclamic, sucralose and aspartame) in food. The procedure involves an extraction of the five sweeteners with a 0.1% (v/v) formic acid buffer solution, sample clean-up and pre-concentration using solid phase extraction cartridges (SPE) and finally, separation on a C18 column (3μm) using 0.1% (v/v) formic acid buffer (adjusting to pH=3.5 with aqueous ammonia solution) / methanol as mobile phase, then analysis and determination with HPLC–ELSD. The results showed that the reasonable linearity was achieved for all the analytes over the range of 0.6μg -20μg with the correlation coefficients r > 0.997. The trueness of the method was satisfactory with recoveries ranging from 85.6%-109.0% at three spiked concentrations, with the relative standard deviations (RSD) lower than 4.0%. The limits of detection (LOD, S/N=3) were between 0.05μg -0.2μg. It is a simple, sensitive and low cost method, and the established method has been successfully applied to the simultaneous determination of five synthetic sweeteners in food.In the third chapter, a method using hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD) was developed for the simultaneous determination of five sugar alcohol (Erythritol, Xylitol, Sorbitol, Maltitol and Lactitol) in suger-free food. We used TOSHO TSK gel Amide-80 3μm column (4.6 mm ID×15 cm), with water and acetonitrile as the mobile phase in isocratic elution, determination with ELSD. The results showed that the reasonable linearity was achieved for all the analytes over the range of 1μg-100μg with the correlation coefficients r>0.998. The trueness of the method was satisfactory with recoveries ranging from 92.5%-99.7% at three spiked concentrations, with the relative standard deviations (RSD) lower than 3.9%. The limits of detection (LOD, S/N=3) were between 0.2μg-0.4μg. It was a simple, sensitive and low cost method, which could be applied to the simultaneous determination of sugar alcohol in sugar-free food.The last chapter mainly introduce the pressurized capillary electro- chromatography ( pCEC) coupled with ELSD. Since the flow of the mobile phase in pCEC is below 1μL/min and ELSD is a detection fit for the common HPLC with a flow in the mL/min, the commonly used ELSD for HPLC needs to be mofified, such as the mofification of nebulization, evaporation, detection section, interface and so on. The last chapter is mainly focused on the system evaluation of pCEC-ELSD. With the LOD, repeatbility, linearity of glucose as major parameters. The results showed that the LOD is 1 ng, the RSD% of peak area of glucose is between 0.91%-2.84, linearity range is about 2 orders of magnitude. We separated 3 amino acids and 5 sweeteners standards with the pCEC-ELSD system. A method using pCEC-ELSD was also developed for the simultaneous determination of three sulfonamides sweeteners, with the advatages of high analysis speed and lower consumption of reagent and sample.