I've started to analyze organic acids by using HPLC a few months ago. For this purpose, I was trained by a master student in the utilization of the HPLC device, and the protocol he transferred me included a overnight step letting water circulating the system.
Recently, I finished the analyses I had to do for the day and let the pumps on by letting the water circulating the system (detector OFF and column removed and substituted by the dummy column), but forgot to stop the machine the following day and when water in the reservoir finished, air started to enter.
Obviously my boss got really angry and informed me that the pumps were the most delicate part in the HPLC device, and if they work longtime without any liquid, they may burn and the pumps are much more expensive than the column because they provide a flow rate a constant or low pressure.
Is that true? Because another assistant professor instructed me in the fact that air entering the system was not so big problem, the column being removed.
I am afraid your boss is correct on this one. The most sensible parts in any HPLC are usually all moving parts, for the pump this is the actual pumps including pistons, seals and check valves (assuming yours is a piston pump). Running them dry for a prolonged time is not a good idea, as the parts wear out much more quickly when there is no liquid around. However: what is done is done, I think most HPLC practitioners have let a system run dry once or twice, and usually there is no huge damage if you come in the next day and "rehydrate" the system properly (i.e. sparge, flush and purge).
The assistant professor is also correct in being more worried about the column - if you pump air through the column for a prolonged time you might actually damage the column to the point of uselessness - which is the more expensive error to fix compared to flushing and sparging the pump again.
Yes its true..pumps are the important part of an HPLC system and air trapped in this part of the system can lead you in a big trouble.
I am afraid your boss is correct on this one. The most sensible parts in any HPLC are usually all moving parts, for the pump this is the actual pumps including pistons, seals and check valves (assuming yours is a piston pump). Running them dry for a prolonged time is not a good idea, as the parts wear out much more quickly when there is no liquid around. However: what is done is done, I think most HPLC practitioners have let a system run dry once or twice, and usually there is no huge damage if you come in the next day and "rehydrate" the system properly (i.e. sparge, flush and purge).
The assistant professor is also correct in being more worried about the column - if you pump air through the column for a prolonged time you might actually damage the column to the point of uselessness - which is the more expensive error to fix compared to flushing and sparging the pump again.
Indeed pumps are precious part of the HPLC system but not as a column. they can be restored and they are too strong to be run sometimes for days at a stretch. the purging of system and priming of pumps couple of times will bring it back to normal... if it was just overnight... we sometimes let run our pumps over the weekend though with the solvents.
The pumps are a sensitive area of the HPLC, if you want an HPLC working well you should not let that happen often. Of course you can do a couple of wet and dry primes and seal wash if necessary, but that only results the system was not dry for a long time. If the system is dry for a long lime, the inlets can be damadge and you need new ones. If you want to let it during the weekend on water reduce the flow, and switch off the flow before finishing the water.
in my world a colums costs about 300 €, a pump 20.000 € just repalcing all the parts discussed by Christof is easily more expensive than the column. Agreed again to Christof, it ahppened to all of us at some point.... but it is not good. so if it happens to a new student in my lab I would give him a talk as well ;-), not because it is a mortal error, but because it can usually be avoided.
Thank you very much for all your answers. I realize now the importance of pumps in such a device :-)
Do you know any book guide that I could use to learn about all this? kind of "HPLC for dummies"? I've been only able to find a lot of material related with the theoretical principle of HPLC, and how to interpret ate chromatograms, but not anything about the practicals issues. And also concerning GC?
Cristina
Hi Christina,
Following two references had been already mentioned in couple of others HPLC discussions posts:
Tips and Tricks of HPLC System Troubleshooting Agilent Technologies. by Inc. LC HPLC Troubleshooting Guide. How to identify, isolate, and correct the most common HPLC problems. by Sigma-Aldrich.
I found them useful.
If you do not have any experience in running chromatography equipment you could start with:
Practical Laboratory Skills Training Guide: Gas Chromatography
Practical Laboratory Skills Training Guide: High Performance Liquid Chromatography.
Kind regards,
Tanya.
Hi Christina,
I have managed to find a pdf copy of GC guide from
http://pubs.rsc.org/en/Content/eBook/978-0-85404-458-0#!divbookcontent
Have a look.
Cheers,
Tanya.
One of the basic principles all the HPLC operators should be considered is the fact that you noted here: " the Pump should not be worked without liquid phase". Its an important practical rule. it could damage the pump and also increase the system pressure.
book suggestion:
Practical High-Performance Liquid Chromatography (By: Veronika R. Meyer)
Thank you very much for all your answers and help.
The equipment in the lab comes from Shimadzu, so I contacted them and asked a manual in english (all information available in the lab is in japanese), but I've had no news until now, so I will try to find the references you provided me.
you boss is partially correct "any pump in the world should not run without liquid" but the damage depends on pump type if your pump is a peristaltic pump I don't thick you have a big problem as no cavitation will happen while if your pump is piston pump you may have a problem. but any way should not let that happen often
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