Natacha - we have had this occur before. It is absolutely critical that your new SGE syringe has free play in plunger movement - some new ones have far too much resistance and should be returned.  Always test your new SGE syringes for free play before installing.

Also, the fact that you are running salty samples does not help either, as over time the salt can cause syringe plungers to stick or jam.  Others on this list have suggested various rinse combinations to help alleviate salt buildup and memory effects - search the isogeochem archives.

The later problem seems a bit more serious and could signal other hardware problems besides a sticky needle - I would remove the old syringe and get a new one that moves freely. Before installing it reinitialize the entire LAS and run the borders mark-out procedure as per the initial set up in the manual. Install the new syringe. See what happens.  If that does not work and you get the same problem again then you may be in for a service call.

Len

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of RIPOCHE Natacha
Sent: Thursday, December 02, 2004 4:40 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] EuroVector LAS


Dear Eurovector LAS users,

have you already have something similar ?

since one week, I started to analyse 18O in urine samples with EA EuroPyrOH/IRMS Isoprime. But the LAS gives problems :

the plunger of the SGE plunger-in-needle syringe is "busy" after around 50 injections of urine sample (which are treated by activated carbon).  The resistence of the plunger in the needle stops the LAS during sequence. So does it mean we must change the syringe type ? or the sample treatment ?


Moreover since yesterday, the LAS stopped itself during sequences (after one or two injections). The screen switched off and restarted with Tray identification. I have tested the fuses and the connexions, which are good.

Any help would be greatly appreciated.
Best regards.

Natacha RIPOCHE

CRNH
CHU Hotel Dieu
3 étage aile Nord
Place Alexis Ricordeau
44093 Nantes cedex 1
France
Tel : 00 33 02 40 08 75 40
Fax : 00 33 02 40 08 75 44