Reaction Method For Determination Of Research And Application

In chromatographic analysis, the sample might exist as several forms or status in aqueous mobile phase. In order to acquire a single symmetric peak in the chromatogram, we could make the sample exist principally as one form by an acid-base reaction. In some cases, the sample had no retention or very small retention on certain stationary phase, so the sample was derived to acquire a suitable retention value. In other cases, some certain detector had no response for some sample, so the sample was transformed into its derivative that could be detected by this kind of detector. Of course, a reaction was necessary for the derivatization step. Thus, all the above methods were combination of chemical reaction and chromatographic separation, an accurate, available and wide-range separation and determination was accomplished, so we, could define all these methods uniformly as reaction chromatography. In this thesis, the method was studied systematically.In terms of the differences on the type and purpose of reaction that was integrated with chromatographic analysis, the thesis was divided into four parts:Review. After searching and analyzing the related literatures, the progress of study on reaction chromatography was summarized, the author illustrated the raising and execution of the methods used in the thesis.Acidic/Alkaline Suppression Reaction Chromatography. In acidic suppression reaction chromatography, the author chose the following samples as analytical objective: four organic acids in electroless plating solution, peroxyacetic acid disinfectant and adenosine cyclophosphate. The formula for choosing the pH of mobile phase in suppression reaction chromatography was deduced and then proved by a series of experiments. The basis of choosing the type and concentration of buffer solution was also investigated in this part. The analytical results of practical samples showed that acidic mobile phase could suppress the ionization of compound with acidic group effectively. The peak symmetry was improved and an accurate measurement was achieved. In alkaline suppression reaction chromatography, the chosen analyte was swainsonine. By adding alkaline buffer solution to the mobile phase, the analyte which existed as the twoforms—molecule and ion—was transformed into a main existing form: molecule. The method not only improved the peak symmetry, but also increased the retention of analyte. The effective alkaline suppressant was a phosphate buffer with pH ~ 7.2.Derivatization Reaction Chromatography. In in-column derivatization reaction chromatography, the chosen analyte was the free formaldehyde in building materials. By adding N, N-dimethylhydrazine (NDMH) to the mobile phase, formaldehyde was transformed into N, N-dimethylhydrazone that could be detected by a UV detector. In this way, analysis of formaldehyde that had no response on UV detector was carried out. It was proved that in-column derivatization reaction chromatography was simpler and more practical than classical pre-column derivatization method in the research.Ion-pair Association Reaction Chromatography. In ion-pair association reaction chromatography, the chosen analyte was synephrine in Fructus Aurantii Immaturus extract. The author investigated the possibility and reality of using butyric acid as ion-pair reagent in ion-pair chromatographic analysis. The results showed that butyric acid whose structure is similar to a surfactant could increase the retention of strong-polar alkaline solute significantly.In the above-mentioned methods, the purpose of the addition of chemical reaction to chromatographic analysis was either to decrease the disadvantageous effect of some reaction on chromatographic separation, or to utilize the advantageous effect of reaction on chromatographic separation and detection. The reaction chromatography that integrated chemical reaction with chromatographic analysis had not only a profound methodological meaning, but also expanded the scope of sample that could be determined by HPLC/UV.