Chromatography Forum

Hello all,

First off, hello to the community and thanks in advance for any help anyone can give me on this.

I have what is probably one of the dumbest problems I've run across in all my time doing this. At some point, someone in the lab had taken apart a column and replaced the end and somehow did not replace the column frit.

So, needless to say, I did not know this prior to putting the column on and starting up the system. I walked away and after coming back got the obvious result, some foaming at the end of the column and had a pressure error with the outlet line from the detector plugged with what I assume to be hardened silica stationary phase (waters ODS-1 column). We are using a really old Agilent 1050 system that is pretty much on its last legs and will likely be the next piece of replaced equipment in my laboratory but I would like to at least coax more use out of it before we just abandon it.

So, after all this happened, I ran some low ph, ~3 mobile phase through the system for a couple days and the detector absorbance reading gradually came back down to a somewhat normal level although I still get some baseline static and the results I get using this instrument range anywhere from perfect to borderline unusable depending on active ingredient being analyzed.

So from what I have read my best options seem to be HF or a pH>10 to be run through the system for hopes of dissolving any residual silica particles that may be left in the system. We don't use HF here so I'm just planning on making some generic MP pH'd to around 10.5-11 and running that through using a union so I don't dissolve any column SP.

My questions lie here: we have essentially all metal parts on this, all the plumbing except the mobile phase reservoir to pump and pump mixing block to AIV. So, if I run this through, would there be any chance I could do any damage to any of the parts in the system? I figured the answer is no since systems are generally made to run from 1-12 but felt that asking people more experienced than myself might not be a bad idea.

Anyway, thanks for any insight anyone might have regarding this issue. I feel pretty dumb for even having to ask this question but here I am and such is reality.

HF may clean out any silica, but will also etch the quartz cell windows. Very high pH probably isn't good for them either.

If this was my problem, I'd pull the flow cell assembly out and disassemble it before trying anything else. You can then flush out the heat exchanger with whatever solvent you want (or, if you're not pushing the sensitivity, bypass the heat exchanger entirely).

Here's a link to the 1050 service manual:
http://mcdonald.ucdavis.edu/uploads/1/8 ... hp1050.pdf

I'm with Tom, you're otherwise suggesting trying to dissolve something that doesn't dissolve easily, using a VERY hazardous material. Strip the cell, bin the tubing.

Thanks for the input guys. I'll give that a shot before I do anything else. I also wanted to clarify that I'm not ever planning on using HF. We aren't even allowed to have it on my company's property, I was just merely mentioning it because it is one of the few things I have read that is able to readily dissolve silica.