On using trap/guard columns

[DJ]

I have a large sample volume to load ( on to a 300SB 2.1 mm C8 column). I have a trap column made of polymeric material (about as retentive as C4). My plan was to load my sample on to the PLRP trap, invert, place in-line, upstream of the 2.1 mm C8 and run my gradient.

Since the PLRP trap is less retentive than the C8 column, I imagine my sample would jump off the trap, onto the C8, where it presumably would stick until MeCN% increased further in order to elute from the C8. On paper this looks like it would be an effective way to concentrate my large sample volume? However, any problems doing it this way?

[tom jupille]

The potential drawback is the pressure capability/compressibility of the PS/DVB. In any case, if your sample is dissolved in something that is weaker than your starting mobile phase, you could just use a guard cartridge packed with the C18 stationary phase. For that matter, if the diluent is sufficiently weak, you can inject a surprisingly large volume directly onto the column.

If your diluent is comparable in strength to your mobile phase, then your analytes may not be retained on the less retentive PS/DVB.