HPLC ferrule stuck into the column

[tom8559]

Dear all, We recently used Agilent 1100 HPLC system to elute HPX-87H column (bio-rad). But we cannot extract the tube inside the column as I showed in the first picture. The front c​onnection part of equipment tube is locked inside the column (which the arrow pointed in the second picture). We did our best to extract this connection part but still failed. I really need your assistances. Does any have any experience in this situation? Thanks.

[dhobbs]

The shape of ferrule and distance from the tip of the tubing varies between column and instrument manufacturers. If stainless steel fitting from one manufacturer is used with a column from another, this very frequently happens. To avoid this in the future, use PEEK finger-tight fittings for column connections.

Now that it's happened: It looks as though the tubing got a bit chewed up by your attempts to remove it, but it's still straight. One option is that you could re-tighten the nut, disconnect the capillary from the other end, leave the capillary permanently attached to the column, and get a replacement capillary for the system.

[M Farooq]

One last resort that has worked for stuck nuts for me (while in desperation) is to sonicate the "offending" end of the column in water while the column is clamped as tightly as possible. Ensure that this end is dipping in a area where maximum power is being seen i.e. maximum ripples in water. Try that as a last resort.

Another option is that if you have a dead old column of the same make, replace the top nut carefully without disturbing the bed. Even if the bed is disturbed, make a small amount of concentrated suspension of silica from the dead column of same make and fill the void.

Good luck!

[tom jupille]

Another trick is to clamp the column in a vise and the use a hot-air gun to heat up the fitting while pulling on the tube. Hopefully the fitting will expand a bit and loosen its grip on the ferrule. HPX-87 is a polystyrene-based packing and will not be damaged by the heat.

[tom8559]

Thanks for all the response. Unfortunately, the outer capillary has just broken when we tried the pulling. (so desperate) I got some information that Bio-rad column won't fit the connection part of Agilent system. But the other end can be screwed out easily. The column is new and I just be told by Bio-rad guys that screwing the outer nut may hurt the column.

[Peter Apps]

Do you have access to a machine shop ? If so they can drill out the bit of tube and ferrule stuck in the end of the column. Make sure that they do not use cutting lubricant.

Peter

[M Farooq]

Take it to a machine shop so they might try to remove the ferrule by pulling out using proper tools. Don't let them use hammers or drills. It is better to sonicate just this end (~ 10 min) and see if it becomes loose.
If this option is not available, the most appropriate way is to find an old column of the same make and design, exchange the screws. I know that companies don't like opening the column inlets, since it affects the bed, but the world does not end by opening the column inlet. Make sure it the column is wet with an aqueous solvent since it prevents sudden drying and flaking of the bed. Before replacing the top screw with another one, ensure that the bed at the column inlet is perfectly flat with a flat spatula, if not fill it up (with the stuff from an old column of the same chemistry). It might lose little bit of efficiency but this is better than throwing it in the garbage. Last option is that see if BioRad can replace it (as a courtesy). Good companies are usually nice with the academic customers.
Moral of the story is that one should not overtighten nuts in any chromatographic connection. Hand tighten plus one quarter wrench rotation is usually enough.

[Consumer Products Guy]

I like to use fingertight nuts and PEEK ferrules for connections to columns, then not only easy to extract any broken ferrule with typical extractor (even Restek sells them, or auto parts store), but easier to get tubing fully seated for no dead volume.

Can you send back to Bio-Rad and have them replace the end fitting? Or I'd just put the column in a bench vise, "bad" end up, and unscrew and screw on a new Bio-rad end fitting. Bio-rad is most likely concerned that if you try this and lose packing, that your performance will be less, and you'd want re-imbursement from them. But if you cannot get that end out, you may have little to lose.

By the way, if I come across a stainless steel fitting where the ferrule is stuck like that (likely due to overtightening) I grab the 1/16 inch part in a genuine Vise-Grips pliers and wiggle a little and pull at the same time, works for me.

[tom jupille]

Replacing the end fitting is possible, but has a high potential for damaging the column (on the other hand, the column is effectively useless at this point anyway). A good precision machine shop should be able to drill into the stub and work it out, but 316 stainless steel is difficult to work with, a slip could ruin the fitting, and it won't be cheap.I know those columns are expensive, but the most cost-effective approach may be to simply replace the column and chalk it up to "learning experience" (if it's any consolation, there is a version of Murphy's law that reads "experience gained is in direct proportion to equipment ruined").

[DJ]

This happens to everyone

I would contact the manufacturer and ask if they'll replace the end. We'd do it for you where I work.

[DJ]

I like to use fingertight nuts and PEEK ferrules for connections to columns, then not only easy to extract any broken ferrule with typical extractor (even Restek sells them, or auto parts store), but easier to get tubing fully seated for no dead volume.

e.

Those 1-piece finger tights suck. Have you found some better? Mine blow over 2,000 psi

[uzman]

@DJ,

If the fingertight fitting blow over 2,000 psi , try to cut the 1cm of tubing , or replace the tubing if possible.
Most of this type problems originated from the tubing , not from the PEEK fingertight.

Normally PEEK fingertight fittings stands well over 4,000psi.

[KM-USA]

I like to use fingertight nuts and PEEK ferrules for connections to columns, then not only easy to extract any broken ferrule with typical extractor (even Restek sells them, or auto parts store), but easier to get tubing fully seated for no dead volume.

e.

Those 1-piece finger tights suck. Have you found some better? Mine blow over 2,000 psi

I've also found that the one-piece fingertight fittings don't hold up to higher pressures; I use the separate fingertight nuts with separate PEEK ferrules, not the one-piece.

[HPLCaddict]

Hm. I usually use these one-piece fingertight fittings:

http://www.vici-jour.com/fittings/peek-ft-color.php
(I think they are sold by quite a few shops).

They are rated up to 350 bar (5000 psi) by the manufacturer, and I've found them to work flawlessly up to the pressure limit of 400 bar of normal HPLCs. They may start leaking when using them with different columns, though. But no big deal, throw the old one away and use a new one. If you're paranoid, just use a new one everytime you change the column. In the end, it's cheaper than a ruined column .

[DJ]

@addict- Yeah. I've had good luck with those.

These are the ones that blow (over 1,000 psi)

http://www.google.com/url?sa=i&rct=j&q= ... 0130969672

I use them only to connect to and from the detector.