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Mike,

I have been dealing with Morgan Advanced Ceramics 
(was Bolt Ceramics). You can find them on the web 
easily enough. I did try getting tubes with less 
than 0.5mm ID from them but couldn't get anything.

The zero volume fittings are from VICI Valco.

Paul

At 05:27 PM 26/03/2008, you wrote:
>Hi Paul,
>
>Thanks for the reply.  Can you shoot me your 
>vendors off list for your 0.5mm ID tubes and 
>zero dead volume fitting?  I absolutely hate how 
>many tubes I break every time I need to change 
>the reactor and would be forever grateful if 
>there is a way to avoid this.  I would even go 
>so far as to say you would deserve some kind of 
>international humanitarian award for this information!
>
>Regarding the peak broadening issue, this is 
>also something Iíve considered, but I guess Iíve 
>always assumed that the transition from a small 
>diameter capillary to the large diameter ceramic 
>tube would trump the turbulence introduced by 
>the wire in terms of chromatography (but I could 
>be absolutely wrong, just my assumption).
>
>Thanks again for the thoughtful comments.
>
>Mike
>
>
>----------
>From: Stable Isotope Geochemistry 
>[mailto:[log in to unmask]] On Behalf Of Paul Eby
>Sent: Wednesday, March 26, 2008 5:12 PM
>To: [log in to unmask]
>Subject: Re: [ISOGEOCHEM] DIY Oxidation Reactor 
>-- Better Chromatography with Smaller Tubes?
>
>Mike,
>
>You need not reduce your tubing OD. With a 
>proper zero volume fitting, it can be any size 
>you desire without affecting the chromatography. 
>We have built our ovens around a 1/8" OD ceramic 
>tube (0.5mm ID) and no longer worry about 
>breaking tubes as we tighten fittings.
>
>Also, I've often wondered though if the peak 
>broadening due to ovens isn't more due to the 
>wire in the tube than the ID of the tube. Does 
>the wire cause broadening by disrupting laminar flow?
>
>Paul Eby
>University of Victoria
>
>At 01:47 PM 26/03/2008, you wrote:
>
>Has anyone had experience with building their 
>own oxidation reactors with smaller ID tubing to 
>improve their chromatography during the 
>combustion process?  I know how much of a pain 
>it is to change these reactors, and while a 
>smaller ID/OD tubing will probably increase the 
>chances of breakages during replacement (not to 
>mention potentially decrease the life span of 
>the reactor), for certain types of analyses the 
>performance gain may make up for it.
>
>Also, is there a reason most users go with the 
>0.1 mm wires instead of something a little 
>thinner (say 0.05mm) to increase the packing 
>efficiency (and thereby reduce dead volume) and also surface area?
>
>I have to admit that this is the first time Iíve 
>ever had to purchase reactors from Thermo (I 
>inherited a stock from the previous technician) 
>and I actually laughed at the customer service 
>rep who gave me the price over the phoneÖ
>
>Thanks in advance,
>Mike
>
>
>****************************************************************************************************************************************
>Michael D. Kubo
>NASA Ames Research Center
>M/S 239-4
>Bldg. N239, Room 327
>Moffett Field, CA 94035
>
>(650) 604-6110
>