Chromatography Forum

We have Agilent 6890s.

I was wondering why it is stilll so difficult to install a column. It's as difficult as it was 25 years ago, particularly for someone with large hands.
Are there any ingenuis third party solutions to this.? If the injection port detached easily, for example, it would help. That way you'd be able to see what you were doing at least.

John

Hi John

If you think that it's difficult now you should have tried it with capillary columns made out of real glass, not this new fangled flexible silica stuff. You had to straighten the end with a flame, and they always broke at least twice on each end.

There have been some attempts at no-twist, quick coupling etc fittings, but they all seem to cost a lot of money for what is essentially a turbocharged swagelok.

Peter

Practice, practice.

Peter - LOL at your comments. Been there done that with the glass capillaries. By the time you made it from a length of glass tubing (unjamming the circular oven repeatedly) and then tried to install it, you usually had 4-5 breaks. What a hassle.

I find loud swearing helps, if not a lot.
Also colleagues who dont know what all the fuss is about (as they have smaller hands and more patience) are handy to have around.
Seriously though, surely there could be a detachable insert which the column could be attached to and then inserted in the top of the oven in a fit-one-way-only manner?
We have ECD and FID. The ECD, used once in a blue moon, is at the front of the oven and the daily used FID at the back.?

Hi John

You can probably swap the positions of the detectors without too much trouble - on Varians it is very easy, on Agilents a bit more trouble I think.

Peter

We're having the GCs serviced in a couple of weeks. I'll ask them about switching the detectors.
I'm sure there was a reason why the ECD had to be in the front - but can't remember why.
Again, apologies if this matter sounds trivial to any forum members.

Several years ago facing the same issue of getting the right depth of column past the ferrule I decided to suggest that a inexpensive plastic female piece of plastic could be made in mass and sold or given away that would allow one to set the ferrule outside the oven. Then it would be an easy matter to insert the column into the detector knowing the right length would result. The idea was dismissed by my management.

The idea was implemented by Phenomenex a few years later.

But if you have a spare inlet insert with the fitting the nut and ferrule screw onto then simply tighten down the nut over your column and seat the graphite ferrule. Then simply measure the length of column past the ferrule and trim the column to the proper length.

No hassle no problem.

best wishes,

Rodney George
consultant

Rodney

Yes we have one of those ferrule tighteners. They're very useful. I hope you got a patent.

My problem is the physical room at the back and top right of the oven when I hold the nut with thumb and index finger to insert the column. The back of the oven restricts easy insertion of the column, as my hand is in the way (if you know what I mean?).

John

One last comment for all users of GC or any instrument.

If you don't like something

COMPLAIN

and threaten to NOT BUY THEIR PRODUCTS IF THEY DON"T RESPOND

and

most importantly

MAKE GOOD ON YOUR THREAT !

The loss of revenue is the only language bean counters respond to.

best wishes,

ROdney George

Hi John

What make of GC do you have ?

Rodney, tempting though it is to boycott a whole GC because the column nuts are upside down, so the ferrule is locked into the nut, and twists the column, I would then have to buy another make, which have even more infuriating characteristics.

I am sure that the forum members could design a non-irritating GC (I'm not talking here about features like detector MDQ or linearity, but about small stuff like how easy it is to remove the side and top panels, or install a column) but we would probably find that six different companies have slapped patents on allthe best bits.

Peter

Peter

We have 2 Agilent GCs and 1 Perkin Elmer.
As you say they all have their good points, and quirks.
We had a guy who was good at interfacing and he rigged ChemStation to everything including Metrohm, Waters and Perkin Elmer (mostly HPLCs)

John

You should be able to move your ECD however you should keep in mind that the make up gas adapter gets heated and cooled by the oven constantly and when you disconnect it and pull it out there is always a chance of a small fracture developing. I've successfully moved them tons of times without any problem, but have had to replace at least 2 of them. I wouldn't let it deter you, just be careful and don't flex it too hard . I would also do my best to prevent any of the insulation from getting into the ECD.

I have giant hands and feel your pain, especially with the 6850. The volume of the oven is basically the same as my fist and replacing the oven shroud is a major pain in the ass. On the other hand, installing a column in the 6850 is a breeze.

I've gotten much better at installing columns, putting a septa on the inlet side in order to hold position easier is very helpful. The method I've found to be easiest is to guide the nut into the threads using two fingers, give it a few turns and then apply slight pressure with 1 finger to the septa/nut in order to hold it in position. Switch to your wrench and finish screwing it in.

It really does seem like they could develop a nut that clips into position rather than screwing in.

I'm sure that the column installation irritation that I have isn't that common or the manufacturers would design an alternative. They probably have the idea that if it isn't broken don't fix it.

I'm surprised Restek haven't come up with anything. The are great at improving the engineering on GCs. I think the EZ twist injection port fittings are a great time and effort saver. A liner or septum can be changed in seconds while the port is hot, without messing up the gas feed lines (no connection to said company I must emphasise!)

John

I may be biased but have always found that the Carlo Erba (now Thermo) split nuts were helpful. Put your ferrule on insert column into injector/detector. Once positioned slip split nut over column and finger tighten to seal Patented ?? Didn't think so ?

Awaits flak as the disadvantage is the graphloc ferrules which whilst being soft graphite for ease of finger tightening can also be tightened with a spanner. Cue issues as some people just keep turning and move the graphite from the steel case into the injector/detector body
Then there is the cost of a ferrule

Quadrex do a quick coupler, but it is expensive. I've never tried it.

Have a look at:

viewtopic.php?t=11792&highlight=

Peter