C18 columns

[Liverpool]

Hi all,

I have this innocent question: The manufacturers make C18 columns for RP HPLC, why don't they make C15, 16 or 17 instead?

[Consumer Products Guy]

tradition: octadecyl was the first common reverse-phase column.

Even chain lengths are available from biological sources, such as fatty acids. Odd chains are essentially synthetics.

[Liverpool]

tradition: octadecyl was the first common reverse-phase column.

Even chain lengths are available from biological sources, such as fatty acids. Odd chains are essentially synthetics.

Thank you for replying me. You mean manufacturers use C18 from biological sources? I first hear about this
How about C8, they can also replace it with C9 or so and it may change the selectivity in general.

[Uwe Neue]

You do not get any significant difference from changing the chain length by one carbon. At equal bonding, even the selectivity differences between a C8 and a C18 column are barely worth mentioning.