Which parameter increases the resolution in size exclusion chromatography?
Increase in column length increases the resolution and increase in column diameter results in high bed volume and hence higher column capacity. The fractionation range and the exclusion limit can be controlled by varying pore size. The smaller the particle size of the gel, the higher the resolution achieved.
How does molecular weight affect chromatography?
As a general rule, the greater the molecular weight or polarity of a compound, the lower its volatility. Both factors have to be considered. For example, a large, non-polar compound may be more volatile than a small, polar compound.
How does size exclusion chromatography separate molecules by size?
Size exclusion chromatography (SEC) separates molecules based on their size by filtration through a gel. The gel consists of spherical beads containing pores of a specific size distribution. Separation occurs when molecules of different sizes are included or excluded from the pores within the matrix.
How does Column length affect resolution?
Halving the column length does not decrease resolution by 50% but by 21%. In practice, the resolution loss is usually 12-15%. This square root relationship means that a large length of column has to be removed before a significant loss in resolution occurs.
How does the size of molecules affect chromatography?
Larger molecules take longer to move up the chromatography paper or TLC plate, whereas smaller molecules are more mobile. Likewise, the polarity of the molecules can affect how far the spots travel, depending on the type of solvent used.
How does molecular weight affect column chromatography?
The larger the particles, the faster the elution. The larger molecules simply pass by the pores because those molecules are too large to enter the pores. Larger molecules therefore flow through the column more quickly than smaller molecules, that is, the smaller the molecule, the longer the retention time.