I second Jen's recommendations.  I usually keep an old syringe that is plugged or perhaps that does not work so good any more, just for the purpose of doing the first core in a new septum.  There is a small degree of float in the septum holder and septum support that I usually start with the assembly more on the loose end, and core it once to ensure things are lined up.  Then I tighten it slightly and core it a few more times.  It is always best to have the retaining cap only as tight as it needs to be. 


If the injector is cold or the septum tightened a lot, it has the habit of acting like a brick.


Hope this helps.





Benjamin Harlow

Manager, Stable Isotope Core Laboratory

Washington State University

School of Biological Sciences

367 Eastlick

Pullman, WA  99164-4236


Office:  509-335-6161

Lab:     509-335-6154

Fax:     509-335-3184


Laboratory for Biotechnology and Bioanalysis (LBB2) Stable Isotope Core




From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Jennifer Lehman
Sent: Friday, October 10, 2014 8:09 AM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Busted Needles


Hi Jeff,


After changing the septa I would manually pierce it with the needle 3-5 times. I am not sure why but it greatly reduced the number of bent needles we saw.


Jen Lehman

W.M. Keck Carbon Cycle AMS Lab

UC Irvine



On Oct 10, 2014, at 7:44 AM, Patrick Griffin wrote:

Hi Jeff,


Are you making your final tightness adjustments when the port is at operating temperature or when the port is cool?  I have had problems with bending and coring in the past but seem to have found a way to avoid them.  After replacing the septum I wait until the injector port is back up to temperature, loosen the cap until the port is no longer gas tight, and then tighten it to a position just slightly more snug than is required to maintain pressure.  This may not resolve your issue because I've never had a Goldilocks problem where there's too loose, too tight, and just right -- instead I have found that a cap tightened at a low temperature is almost always too tight for operation once the temperature returns to operating specs.  Your mileage may vary, but I figure even one forty dollar syringe is worth my two cents.  Hope it helps.




Patrick Griffin

Department of Geological Sciences

Indiana University


On Fri, Oct 10, 2014 at 9:54 AM, Jeff Salacup <[log in to unmask]> wrote:

Hello ever-helpful collective brain,


We're having problems either bending or plugging our Thermo 10uL syringes (PN 36500525). It usually occurs after a septum change (septum PN Restek 27116). It seems that if I don't tighten the septum cap enough, the needle bends, if I tighten it too much the needles effectively cores the septum, plugging the syringe. We're running a Thermo Trace Ultra GC with a Thermo AS3000 autosampler. I've been thru 4 syringes in the past 2 days ($$) and am wondering if there is some trick I'm unaware of.


Any help would be huge. 


Thanks again,



Jeff Salacup, Ph.D
Lecturer | Stable Isotope & Biogeochemistry Lab Manager


Website: http://blogs.umass.edu/jsalacup/



“… it’s not your life. It's life. Life is bigger than you… Life isn't something that you possess; it's something that you take part in, and you witness." –Louis C.K.