What do you do if you receive the gift of an HPLC system of unknown breeding? In a recent enquiry, a reader indicated that when he moved into a new lab, the prior occupants left an HPLC system sitting on the bench. They thought it was working well when it was last used but judging by the thickness of the dust on the case, it had been a long time since it had been used. What do you do in a situation like this?

One thing you will want is a user’s manual if there isn’t one included – after all, it is nice to know how to run the thing and make some basic repairs. You may be able to get this from the manufacturer if the instrument is still being actively supported or you may be able to find one or free on the internet. If all else fails, post a note on Chromatography Forum and some kind-hearted soul will surely share a copy with you.

I’d probably assume that whoever used this last just turned their back and walked away, so who knows what lurks within. This means a fairly major cleaning and at least minor maintenance session is in store. I would remove the column and throw it in the trash. Connect a piece of tubing in place of the column and route it to waste. Unless you suspect otherwise, you can assume that the system was last used under reversed-phase conditions and had some buffer left in it. So you need to flush it out. I would start by making a litre of 50/50 methanol (MeOH)/water and seeing if you can get it to pump through the system. Put the inlet tubing in the reservoir, open the purge valve on the pump and prime the pump. It may take a bit of work to get all of the air out of the tubing and pump, but if you’re lucky, you’ll get a steady flow from the purge valve. Close the valve and see if you can get mobile phase all the way through the autosampler. Repeat this process for each of the other solvent lines. Once you’ve purged all the lines and can pump solvent through each line, it’s time to do some pump service.

   At a minimum, I would replace the pump seals and frits on tubing in the reservoirs. I would also sonicate the check valves for a few minutes each in 100% MeOH or if I felt rich, replace them with new ones. The tubing between the reservoir and the pump is probably OK, but replace it if it looks cracked, kinked, or discolored. Clean out the autosampler, purging all lines to be sure they are clear.

   Once everything is clear and mobile phase will flow through each line, connect the tubing from the autosampler to the detector and see if you can get solvent to flow through the detector. I suspect it will work fine. There isn’t much you can do other than flush the detector cell, anyway. If the detector lamp does not turn on, you may need to replace it. Next, put a column on the system and see if you can generate a chromatogram. I’d probably start with something like the column test mixture that the column manufacturer uses for column testing. Otherwise, use a very simple and dependable method, injecting standards instead of real samples.

   At this point you’ll be able to decide if you were left a useful piece of equipment or a piece of junk. Assuming that it works well enough to encourage you, put it through its paces and see how it works. Undoubtedly there will be more maintenance to do before you’re completely happy with the system.

   As an alternative to all this work, you could just call the HPLC manufacturer and schedule a service call and leave all the work up to the service technician. But that wouldn’t be as much fun….

This blog article series is produced in collaboration with John Dolan, best known as one of the world’s foremost HPLC troubleshooting authorities. He is also known for his research with Lloyd Snyder, which resulted in more than 100 technical publications and three books. If you have any questions about this article send them to TechTips@sepscience.com

Published  Feb 9, 2021

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