MICROSCOPIC APPROACH OF RETENTION AND DIS PERSION PHENOMENA IN CHROMATOGRAPHY

The understanding of a chemical process is clearly related to the ment al representation of the various microscopic phenomena occurring durin g this process. Because the microscopic behaviours are the basis of al ly process, they were used to perform simulations with the aim to help students to create a link between both microscopic and macroscopic wo rlds. During the chromatographic elution, the mobile phase moves along the column with a constant velocity carrying solute molecules. At the same time, these solute molecules fan diffuse in the mobile phase, mo ve from the mobile phase to the stationary phase and come back from th e stationary phase to the mobile phase. Such random walk processes are well simulated using molecular automata: numerous microscopic events (diffusion, phase transfer and elution) are simulated in the microscop ic word to mimic the chromatographic process. Simultaneously the resul ting macroscopic chromatogram is drawn. So the macroscopic retention p arameters (retention volume, capacity factor), and dispersion paramete rs (variance, efficiency) occur as a result of microscopic events (dif fusion, phase transfers, elution), and also depend on the chromatograp hic system (column length, elution speed). Several presentation softwa re based on this phenomenological approach are described.