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- Posts: 3
- Joined: Thu Nov 15, 2018 1:34 pm
So I have a problem with one of our PE 200 binary pumps. We were seeing something that should have been a sharp peak appearing as a blob over 15 mins during a standard gradient run (20% MeCN to 95% MeCN and then back to 20%). I've managed to trace the problem to just the pump. When I have it run at 10 mL/min 100% Solvent A it is fine and when I have it run at 10 mL/min at 100% Solvent B it is fine. BUT. When I ask it to do a mixture, (e.g. 50:50) it seems to pull solvent exclusively from solvent A at the full flow-rate and not touch solvent B. I figured this out by turning the pump on at 10 mL/min 50:50 A:B and removing the tubing from each solvent bottle for a few seconds. For solvent A, you quickly see it pulling air but nothing happens with solvent B.
Any ideas what the problem could be?