pump pressure problems

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

5 posts Page 1 of 1
hi all

i am having problems with my pump. unsure if it is trapped air or something else.

ive purged the pump a lot, all 4 channels.
also done with isopropanol with a restriction after the pump.
tried letting it settle over the weekend, ive seen this helps before allowing the bubble to escape more easily.
but no luck. i suspect it may not be air.
i have also changed the ptfe frit. this was a little dirty. i changed it a couple of months ago - could this be a piston seal issue?
and now i cannot build pressure like before... normally i see around 90 bar with 0.5 ml/min 99/1 Aq/Org and i see only 20, with huge fluctuations.

i attached a pressure profile.i use an agilent 1260 quat pump pumping 100% aq (very low conc buffer) around 1 ml/min. pink and blank are 2 different injections
Image
an update:

i disconnected the column and pump @ 1ml/min 100% A and this is my pressure profile. any ideas?

Image
I see no image files or data in your posts.

Sounds like you have not properly primed the channels (or degassed the liquid. Is your degasser broken?). You mention you have an Agilent 1260 series pump. These are some of the most reliable and easy to use HPLC pumps available, with one exception. Some idiots in Agilent's marketing dept deleted the standard Active Inlet Valve (AIV) on their "Value" line pumps turning them from 100% reliable to 20% reliable pumps. This was one of their most profound marketing mistakes in the industry (should have fired everyone who signed off on that idea)! The good news is that if you were sold ones of those "AIV-less" pumps, you can simply order the AIV parts (the connection tubing and valve, it just plugs right in) and install it, leaving you with a 100% reliable working pump once again. There is no reason to use that pump w/o the AIV installed as that is what makes those pumps so reliable (no sticking check valves). So, if your is one of those, please upgrade it ASAP so you can avoid these issues.

*To help you most of all with these types of basic HPLC problems, please find someone local who has 5+ years of industrial chromatography experience with Agilent brand system to provide basic training in the operation of the HPLC system. Training is worth every dollar and will get you up to speed much faster than trying to sort things out on your own. These are easy things to sort out, in-person, and very difficult to do over the web.

Here are a few links that may help you troubleshoot the pumping issues:

"Tips and Advice for Priming your HPLC PUMP (or similar pumps, FPLC or UHPLC Pump)"; https://hplctips.blogspot.com/2020/09/t ... -hplc.html

"Diagnosing & Troubleshooting HPLC Pressure Fluctuation Problems (Unstable Baseline)"; https://hplctips.blogspot.com/2014/01/d ... -hplc.html
Another simple thing to check is the filter on the line in the solvent bottle. I have seen algae grow in the water one and cause many problems because it makes a vacuum on the channel and causes air bubbles to form within the flow path.
The past is there to guide us into the future, not to dwell in.
hi both thanks for your replies!
if you right click on the image and click open in a new tab you can see them.

all lines have been primed. for hours and hours. high flow and low flow, water and isopropanol. priming is definitely not the issue here.

ive checked all the inline filters, no algae growth.

the check valves ive loosed and allowed mobile phase to leak out to help push out any air that could be trapped there. i will see what our technician thinks about the valves when they come.

thanks!
kate
5 posts Page 1 of 1

Who is online

In total there are 2 users online :: 1 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: John Guajardo and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry