by
unmgvar » Fri Sep 16, 2011 1:09 pm
i remember a dionex seminar where they explained who we should decided if we needed a HPG or LPG pump in their UHPLC system
it basically came down to the volume delivered by the pump
in their LPG the piston stroke volume is of 80ul
so for gradients of runs under 2 minutes the baseline noise fluctuation and drift associated to the LPG would be greater then for a HPG pump
an effect of step drifts would also appear for very shallow gradient changes, generally used in peptide maps for example.
for those cases an HPG would render better gradients. everything in between is kind of the same
but a HPG pump costs a lot more, requires a lot more maintenance, you basically have 2 pumps, 4 check valves, double the amount of piston seals.
another down of the HPG is that you need to be smarter with where you put your water in order to wash the buffer line. and you cannot do 3 solvent gradients, but if you get to needing that then i would not like to be in your place.