Hplc Columns Externalities And Its Correction

Nowadays, with the rapid development of technology, the method of scientific analysis is becoming more and more advanced. The HPLC is widely employed to characterize and quantitative analysis a variety of substances by many research and teaching institutes. The HPLC is more sophisticated and the detect limit is small owing to the development of manufacturing technology. Because the HPLC is mainly applied in biology, pharmaceutic and environment protection, and the components of the sample are very complex, so the generation of the overlapped peaks is inevitable, bringing about the difficulty to quantify them accurately. Now the main HPLC station is using the middle-cutting method to quantitative analysis. However, the chromatography peaks are asymmetrical according to the chromatography theory. With the influence of both thermal and kinetic factors, and with the HPLC more sophisticated, the asymmetry is more obvious. The application of the middle-cutting method is unreasonable, and the deviation is appreciable. Therefore, a more acceptable method must be found.The main work was focused on the factors, which cause the asymmetry of peaks. The original peaks are modified according to the asymmetric factors. And theorically, the modified peaks are narrower and more symmetrical compared with the original peaks. Then the overlapped peaks were processed by middle-cutting method, and the deviation can be reduced.In HPLC, the asymmetry of the peaks is caused by columm effect and extra-column effect. We only considered the extra-column effect because of the following three reasons: 1. The extra-column effect is dominant compared with the column effect in the more sophisticated HPLC instrument. 2. The column effect varys with the different manufacturers and the general resolution is hard to establish. 3. The column effect consists of both kinetic and thermal factors, and the model is comparatively complex.In our research, the connection tube was studied under every condition such as different diameters, length, flowing velocity and diffusion coefficient. And theinfluences to the curves of the flowing out were investigated. We established a mathematical model which was solved by finite analytical method(FAM). And the elution of the components in the connection tube was simulated. Moreover, we establish a similar model to modify the actual chromatography peaks, then we process the overlapped peaks with the method of middle-cutting and get reasonable results.