Chromatographic separation modes

Figure 8. Optimization of eluent composition for the LACCC separation of polyester (a) molar mass dependence of retention in different chromatographic separation modes and (b) corresponding calibration curves.

Matrix The components within a mixture that provide support and structure but are not directly relevant to the analytes of interest. Blood is an example of a matrix in the examination of drugs of abuse Mobile phase The phase that carries the analyte through the stationary phase and is used to influence the chromatographic separation Mode of separation Denotes the mechanism by which the separation takes place. It is characterised by the stationary phase and the solvents used to elute the analytes of interest. It can be classed as reversed phase, normal phase, ion exchange, and chiral chromatography... 

The transition from one to another chromatographic separation mode by changing the temperature or the composition of the mobile phase for the first time was reported by Tennikov et al. [8] and Belenkii et al. [9,10]. They showed that a sudden change in elution behaviour may occur by small variations in the... 

In a chromatographic process, a solute is equilibrated many times between the mobile and stationary phases during passage through the column. Each equilibration is equivalent to one equilibrium stage or one theoretical plate. Though in SEC, the concept of the so-called stationary phase, as in other chromatographic separation modes, is not definitive, the theoretical plate number N derived from the plate theory is still used as a measure of column efficiency. 

In any chromatographic process, separation results from molecular interactions between the solute molecules and the stationary and mobile phases. Various types of forces maybe involved in such mechanism in the case of lipids, hydrophobic interactions play a major role, while ionic, dispersive, and polar interactions are involved to a greater or lesser extent. It depends on the liquid chromatographic separation mode, finally. 

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