How does a C18 HPLC column work ?

    How does a C18 HPLC column work ?

Answer - A C18 column is a reverse phase HPLC column which has carbon chains bonded to the silica particles inside the column. The C18 tells you how long the carbon chains are, in this case there are 18 carbon atoms in each chain. This type of phase is hydrophobic and non polar molecules will interact with it when they pass though the column. So if you had a sample which had two components in and one was more hydrophobic than the other, the least hydrophobic component would elute first followed by the more hydrophobic molecule. To help drive these molecules off the column a mobile phase with a high solvent content is used so that the mobile phase is more hydrophobic than the column, this will cause the molecules to interact less with the column and stay in the mobile phase for longer, until they eventually elute out of the column and then travel to the detector for analysis.