Chromatography Forum

I am using a Waters Aqcuity UPLC system. Sometimes (probably 1 in 3 times) when a sample is drawn and placed into the loop, I immediately receive an Empower error message that states "Message 2311 Instrument Error...Sample pressure low (98.4): possibly no wash solvent or needle damaged" and my sample set stops.

My instrument method allows pressures between 0 and 15,000 PSI (it won't allow me to go lower). I have made sure the needle was OK and that all solutions, including strong/weak solvents, are thoroughly primed. The injector has been primed numerous times. I have turned off/on the instrument. I still keep getting this frustrating error every few injections. What should I do?

Totally replace the needle and recalibrate.

It can be the washing station septum that is loosing pressure.
Tighten the washstation by putting a wrench on the top of the right stainless steel "column" of your washstation. Only turn a little bit (1/8), and see if the problem re-occurs. Try this 2-3 times, and the problem should be gone.
Dont try this more, as your septum could be to tightened.

Ace

We were getting this message on a regular basis with our Acquity system as well, only when we were doing full loop injections (10ul). what worked for us was to have the weak wash in the same ratio of aqueous/organic as the mobile phase, and prime the needle wash lines 15-20 times. after that, it works like a charm. the fact that you are getting 98.4 as a sample pressure makes it sound like the septum is a little loose. when we would get our "sample pressure low" error, our sample pressure was at 5-20.