Topics - Method Development
Method development in chromatography is the setting up of an analytical procedure that will be appropriate for the analysis of a particular sample. It starts with the choice of the technique, gas chromatography, liquid chromatography or thin layer chromatography (and under applicable circumstances, possibly preparative chromatography). For example volatile substances are best separated by gas chromatography as the technique provides the best resolution, the shortest analysis times and the highest sensitivity. The next choice will be the phase system that should be used. This will be based on the interactive character of the components of the mixture to be analyzed. The choice will range between predominantly, ionic, polar or dispersive which, respectively, will indicate and an ion exchange stationary phase, a polar stationary phase (hydrophilic) or a dispersive stationary phase (hydrophobic) or a clever blend of two or all three. Having chosen the stationary phase, if liquid chromatography is to be used, then a complementary mobile phase must be selected. Column length, column diameter and, for a packed column, particle diameter must then be chosen to provide the necessary efficiency to effect the separation in the minimum time. The detector must then be chosen to provide the required sensitivity, the necessary linearity and if needed the desired specificity. These are some of the basic choices but there are many others to be made, an internal or external standard, the method of sampling, the need for gradient elution, or temperature programming, detector sensitivity etc. Efficient method development
requires expert knowledge of chromatographic science and extensive practical experience.