Fast Chromatograpy - Productivity of Chromatographic Methods

There is growing pressure to increase productivity in chromatography, leading to research and development of faster and more efficient methods. However, there are several factors that limit the speed of chromatography: the number of compounds to be separated, the time required for sample preparation, and the speed of the autosampler.

Sample dissolution

Dissolution, one of the most important chromatographic parameters, determines how quickly a mixture of compounds can be separated. The peaks of the individual compounds must have sufficient resolution and selectivity.

GC with a large number of compounds

Especially when there are a large number of substances in a mixture, resulting in many peaks to be separated, GC is the method of choice because the columns have many separation stages. The prerequisite, however, is the fugacity of the substances without them decomposing. This is a limiting factor for many compounds.

Capillary electrophoresis

Capillary electrophoresis is a good alternative, especially for charged particles. However, sample preparation is an additional time consuming task. If autosamplers are used, the capacity of the instrument is the limiting factor in terms of time required. Methods such as UPLC, UHPLC or capillary electrophoresis are mainly used to separate compounds that do not require preparation.

HPLC with sample preparation

HPLC is the best option when sample preparation is required. In order to be able to use all conventional HPLC instruments, columns larger than 3 mm in diameter should be avoided. As far as the method is concerned, an isocratic eluent composition should be chosen, since here, among other things, the reconstitution time offers a great time saving potential.

In order to meet the productivity requirements for this method, the financial factor should not be neglected. Cheap equipment is fine as long as it meets all FDA requirements. In addition, the use of solvent recyclers is another way to reduce costs.

Thin layer chromatography: effective and simple

Thin-layer chromatography (TLC) is a very effective and simple method. More than ten samples can be easily separated in 15 minutes. The ease of use means that no sample preparation is required and costs are low. Coupling with MS instruments further emphasizes the importance of this method.

Conclusion

In summary, there are many factors that determine which method is appropriate. The method with the highest technical standard is not always the most efficient choice.