Hi all,
We’re trying to automate the elution step on a positive-pressure SPE setup where we have 96-pressure channels on the head.
In the setup, we have 96 cartridges in an adapter, with a 1.3 mL deep-well plate underneath as the collection plate. I ramp the pressure from 100 mbar up to 600 mbar, hold at 600 mbar for some time, then lower it again.
With a low number of cartridges this mostly works fine, but with higher numbers (more than 32) I run into the following problem: foam forms at the cartridge outlets (the eluent is 50% acetonitrile), and this foam spreads across the deep-well plate, leading to non-uniform levels and cross-contamination. Notably, I don’t see this with water, it only happens with the 50% acetonitrile, which makes me suspect it’s related to the lower surface tension of the organic solvent.
Do you have any suggestions?