Have you tried mass calibrating again. Taking a hiatus from the spec to drink beer and play guitar hero without the rugrats (how old are yours now, both of mine are in university) never hurt nobody. 

Water and Aquatic Sciences Research Program
University of Victoria, Department of Biology
PO Box 3020, Station CSC,
Victoria, BC, Canada V8W 3N5
(250) 472-4789
----- Original Message -----
From: [log in to unmask] href="mailto:[log in to unmask]">William Mark
To: [log in to unmask] href="mailto:[log in to unmask]">[log in to unmask]
Sent: Friday, January 25, 2008 8:48 AM
Subject: [ISOGEOCHEM] Halted Runs - Not always a good thing.

Hello All

I have been experiencing and intermittent “event” for a couple of months now that is getting worse and needs to be resolved – hopefully someone can toss me a clue before running to the default , filament replacement.

This “event” has been seen over a couple of different filaments installed over a 3 month period; when it’s running, the sensitivity, stability and sample analysis have been very good. I have tried re-tuning several times with very little change in tune settings or the problem. I do daily Mass Jump testing etc…

Lately, with the increased frequency of this “event” the spec has had more stability issues and notable HV peak centre shifting during Mass Jump testing.

In a nut-shell;

We have a Delta Plus running solid C/N EA samples. At some point during the run (sample 8, or 53 or 111 – anytime) after analysis the CO2 Ref pulse and jumping back to Nitrogen for the next analysis, I get a “Fatal Script Error”. This is a drag not only for lost analysis time but it leaves the Ref Valve open all night.

It seems, once the jump back to nitrogen is complete, the Ref gas is opened and before it can run the peak centre, the run is halted.  I have noticed at this time, that not only is the spec blind to the N2 Ref Gas peak but even the background levels drop to unfamiliar readings, as though it is no longer even looking in the proper neighbourhood.

After sitting for a few seconds, to a few minutes, “blip” the proper backgrounds come up (or the Ref Gas peak, if it is still open).

I am ready to pull the filament out and try another but I was wondering if anyone thinks it could be some other “flakey” electronics/ board. It seems not to be landing where says (or thinks) it is, after the jump to back to nitrogen.

Any thoughts would be greatly appreciated.

Have a good weekend.

I am off to a cottage with my 2 younger brothers (leaving our families behind), to drink beer, watch movies and play Guitar Hero. It may not help but it can’t hurt.

            Bill Mark

            Isotope Technician
            Environmental Isotope Lab
            University of Waterloo
            Phone (519)-888-4567 Ext 36747
            FAX (519)-746-7484