Simulated gas standards

["Andrew Welsh" <welsha@kbpnfs01.eskom.co.za>]

Hi all

Earlier this year our laboratory purchased 2 4-litre marinelli 
simulated gas standards for calibrating our detectors.  We 
deliberately purchased them from 2 different vendors (in the USA) as
we thought it would be desirable from a QC point of view.

Unfortunately, they do not agree well with each other and we of 
course do not know which one we should use to perform our 
calibrations.  The one is about 15% higher than the other one, over
the whole energy range.  

Obviously I'm not going to name the vendors on this list, but they
both claim to be NIST-traceable.

Has anyone on the list ever experienced anything like this?  Can
anyone suggest some tests which we could perform to get to the bottom
of this?

Thanks
Andrew


Andrew Welsh
Chemistry Development Section
Koeberg Nuclear Power Station
Private Bag X10
KERNKRAG 7440
South Africa
Tel: +27 (0)21 5504298
Fax: +27 (0)21 5505117
E-mail: welsha@kbpnfs01.eskom.co.za