Quantum Chemistry Of Chromatography

With the increased performance of chromatographic separation, in chemical analysis, even minor differences in the molecular structure can also be separated. But the qualitative analysis is still the most difficult. Currently, the most common method is the standard sample. However, it also has many disadvantages:there must be a lot of chromatography standard sample; the reliability is not high, a peak may correspond to multiple standard samples, need other means to be determined.In this thesis, we use quantum chemistry methods to simulate chromatography separation process, explain and predict the retention of different solutes in different stationary phase by quantum chemical calculations. The main work is divided into three parts:(1) The simulation for the static adsorption of the imprinted polymerThe first of all is the synthesis of molecularly imprinted polymers (MIPs). adsorption static adsorption ability of MIPs for tryptophan were measured by Ultraviolet (UV) absorption measure technology. Imprinting polymer is seen as a supramolecular systems, then simulate adsorption process. The results match with the experimental values.(2) The simulation for the gas chromatographic analysis of the sesame oilPrepared samples were separated and detected by GC under the optimal conditions. The main components of fatty acids in sesame were identified by GC-MS, and26compounds could be identified. The parameters of separation system, such as binding energies、mulliken atomic charges、bond length, were calculated by Gaussian method. The total energy difference and the chromatographic retention have significantly correlated. This method can predict the order of separation of some substances, screen a suitable stationary phase, and simplify the separation of the pre-pre-experimental part.(3) The simulation for HPLC analysis of the benzoic acid and caffeineThe Students experiment, HPLC analysis of food additives in Drinks, is simulated by Gaussian method. The results match with the experimental values, further validating and interpretating. Than the chromatographic separation mechanism is further illustrated with quantum chemistry, which explains the actual role of selective intermolecular forces.