Chromatography Forum

Hi Everyone,
I am new to this forum and new to chromatography, so I hope you can help me out. I am having many problems with fitting systems and need some good tips. For example.

1) It seems that if you change a column you often need to reposition the ferrule in order to make an exact fit. If you don't do this the chromatography can look horrible. Getting the ferrule position right is quite tricky so are there any hints on how I can do this as quickly as possible?
2) I found that some fittings only work with rheodyne valves and some only work with valco valves. I often get mixed up and use the wrong fitting on the valve. Are there any fittings out there that work on both valve types?
3) Things get even harder on our UHPLC system. Are there any easy to use fittings for UHPLC?

Thanks in advance for all your help

Zohan

Some manufacturers, for proprietary/captive reasons, have different length fittings, so correct-length stainless steel fittings and different tubing/fittings would be required for changing from manufacturer to manufacturer. An alternative is to use fingertight-type fittings like we usually do; with these, one simply pushes the tubing through the ferrule as far as it goes (until it butts out) while tightening the fingertight nut. Of course, if one has three hands this is a little bit easier, but one soon gets the hang of it. We use these on both PEEK and stainless steel 1/16 inch tubing.

Consumer products guy provided some good advice.

I can add a few comments that may be helpful:

There are a few common types of fittings for HPLC tubing, usually coned 10-32 port or flat-bottomed 1/4-28 ports. Most of the high pressure fittings are 10-32 (Parker, Valco, Waters, etc). Rheodyne uses smaller M4 threaded ports on some valves, Valco uses smaller 6-40 threaded ports on some of theirs. There is occasionally an odd duck manufacturer who uses M6 fittings or 5/16-24 (LDC) fittings.

You can use PEEK nuts/ferrules on PEEK or steel tubing for most applications at standard HPLC pressures. Peek doesn't have to permanently swage to make a seal, so you can reposition the fittings and ferrules to adjust to different ports.

For high pressure applications use steel tubing and a permantly swaged steel ferrule. Its important to keep the nut/ferrule matched to a specific port or column once you've swaged it, and be sure to use Zero-Dead-Volume technique when initially swaging the ferrule. (more on ZDV-technique later)

If you need to change columns or ports with steel tubing, you will have to cut the end of the tubing off with the swaged ferrule and start over. Otherwise you may have too little or too much tubing in front of the ferrule, which will cause problems. Too little tubing and there is a large dead space in your system where mixing will occur, this will wreck your efficiency and resolution. Too much tubing in front of the swaged ferrule, and the tubing will bottom out in the port before the coned ferrule contacts the walls of the port - it won't seal.

Here is a great solution for UHPLC connections with 1/16" steel tubing:
http://www.optimizetech.com/opti-shop/i ... ts_id=2125

This nut and hybrid ferrule combination will seal at extremely high pressures (tested to 30kpsi), but the ferrule can be released and repositioned for use with any 10-32 port. So when you change hardware, you don't have to cut off a steel ferrule and start over - the EXP nut/ferrule can be reused many times for flawless UHPLC connections.

Optimize even has a hand-tight version which seals to 10-14kpsi depending on your hands. Absolutely no tools required!

/plug

more on ZDV technique:

1. Be sure to start with quality tubing that has square-cut ends

2. Put the nut onto your tubing, then the ferrule. Start with the nut/ferrule farther from the end of your tubing, so the tubing bottoms out completely before the threads of the nut engage the port.

3. Thread the nut into your port by hand, making sure that it isn't crossthreaded

4. Push the tubing into the port to keep it fully bottomed out while you tighten the nut. If using handtight fittings, keep pushing the tubing into the port while you tighten fully by hand. If using steel nuts/ferrules, keep pushing the tubing into the port while you tighten the nut with a wrench to about 1/2 turn past snug to swage the ferrule.

5. Pressure up and check for leaks. If you find a leak first try to tighten the nut another 1/4-1/2 turn. If it still leaks, stop what you're doing because going tighter will probably just cause problems. remove the tubing and start over (with steel you'll have to cut off the end of the tubing and ferrule, with PEEK or EXP fittings simply push the nut/ferrule back away from the end of the tubing).

Please check out our new fittings for ultra-high pressure (and high-pressure). It is holding the tube with serrated collet and not damaging ferrule. You laso have a tool to release the tube from the fitting. Fitting has a lot of benefits including price:
http://www.sielc.com/Products_Fittings_UHP.html

You can laso look at this chart for fittings:
http://www.sielc.com/Products_Fittings.html

Contact me if you have questions.

I'm usually a bit reluctant with posting to this forum as I feel that vendors should not misuse it as a platform for advertizing.

However, after having read the above and being the responsible Product Manager at Dionex, I decided to introduce you to our revolutionary new HPLC and UHPLC fitting system. We call it Viper. You may may say that revoutionary is a big word and one should be cautious with using it, but just consider the fact that Viper removes exactly all the drawbacks mentioned in the previous posts.

Viper provides guaranteed zero-dead-volume connections, regardless of the counterpart, valve or column. It seals and reseals easily and without force. No tools and also no 3rd hand required. Fingertight up to 1000 bar. The secret? It seals at the capillary tip and does not rely on ferrules or ferrule-shaped parts.

Check this out:
http://www.dionex.com/en-us/Dionex_HPLC ... 70654.html

At the bottom of the page you can download a document that provides more detailed information.

Best regards,
Wulff

Wulff Niedner
Product Manager LC
Liquid Handlers and Column Compartments
Dionex Corporation

Wow you guys are shameless,


At least I offered some basic help along with my plug

Now that we've got a bandwagon, anybody else wanna jump on? There must be one or two other HPLC fitting manufacturers around here somewhere (looks under solvent cabinet, behind autosampler).

Hazmat,

It was so well explained by you that I had nothing to add, and after I saw your link I just decided to offer a different design/solution

Actually, I'm a fan of Upchurch fittings and tubing, and their catalogue is a mine of information on tubing and valves, backpressure, internal volumes, etc.

They also offered an excellent free introductory handbook "all about fittings" by John W Batts IV dated 2003. I couldn't find a pdf of it on their current site, but it may be hiding in one of the site menus.

I have it as a 4MB pdf that I downloaded a year or two ago - so if you can't find it, please email and I'll send it to you. Check their site first, as there may be copyright issues about propagating the booklet. Obviously, it doesn't cover the UPLC, UHPLC, etc. systems.

http://www.idex-hs.com/Upchurch-scientific.aspx

Please keep having fun,

Bruce Hamilton

The "all about fittings" booklet can be found here:
http://www.teknolab.no/pdf/Upchurch_All ... ttings.pdf

Wow - thanks for all feedback. I'll try what I can with the ZDV technique. Also, the upchurch and Dionex fitting systems look interesting. I will try them out and let you all know what works best for me.

I tried the ZDV system with my existing capillaries and I found that it worked well, but that it took a long time to learn to use it effectively. Next I purchased the Dionex fitting system and it worked perfectly first time. I could fit every column with ease. It was so good that I didn't bother buying the Upchurch system for comparison.
We are now going to fit every LC system in our lab with Viper - it is much easier to do this than to train everyone on ZDV.

You shouldn’t choose a different fitting manufacturer because oftentimes, the length is not the same. That is the usual problem if one had chosen to buy a different brand. Better stick with the brand that you already tested when it comes to quality and durability just to be sure.

I have been following this thread (read: lurking) and tried a few fitting solutions from the afore mentioned manufacturers.

I would like to thank HAZMAT for his post regarding the EXP Hand-Tight fittings as we have recently outfitted our entire lab. I visited the Optimize Technologies booth at ASMS and was quite pleased they offered such a simple hand-tight, 20,000+ psi, option I could use many times over in various types of ports (Waters, Parker, etc.) with an auto-adjusting ferrule.

The ROI for this fitting is also great as I have sealed and unsealed one of the Titanium-Hybrid PEEK ferrules, in various port types, over 20 times.


Thanks to all for the advice on this topic and I look forward to becoming a more active community member in the future!

Best,
Melle