Just as a matter of interest, how comparable are re-run bicarbonate results with the original values on both your systems? Even if there is an evaporation guard gas exchange would still be possible, so this rather crude experiment would show what effect diffusion has realtive to calibration...
Dave
Dr David Hardy
Senior Scientist (but not for much longer!),
Biomarkers, DSRD,
Bld: 503/1.04F,
IPC: 699,
Pfizer Ltd,
Ramsgate Road,
Sandwich,
Kent CT13 9NJ
Tel: +44 (0)1304 640619
E-mail: [log in to unmask]
LEGAL NOTICE
Unless expressly stated otherwise, this message is confidential and
may be privileged. It is intended for the addressee(s) only. Access to
this e-mail by anyone else is unauthorised. If you are not an
addressee, any disclosure or copying of the contents of this e-mail or
any action taken (or not taken) in reliance on it is unauthorised and
may be unlawful. If you are not an addressee, please inform the sender
immediately.
Pfizer Limited is registered in England under No. 526209 with its
registered office at Ramsgate Road, Sandwich, Kent CT13 9NJ
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Dooley, Kent
Sent: 23 February 2011 19:20
To: [log in to unmask]
Subject: Re: Bicarbonate assay
The problem may not be due to diffusion in your laboratory. However, some manufacturers may assign calibrator values based on the practices of labs which do not so assiduously handle their samples. Thus, using such calibrators in your lab would cause factitiously high bicarbonate values.
Kent
Kent C. Dooley PhD FCACB
Clinical Chemist
LifeLabs
3201 - 4464 Markham Rd.
Victoria BC V8Z 7X8
tel: 250 881-3100 ext. 2120
email: [log in to unmask]
web: www.LifeLabs.com
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of COLLINS MICHAEL (RM1) Norfolk and Norwich University Hospital
Sent: Wednesday, February 23, 2011 1:53 AM
To: [log in to unmask]
Subject: Re: Bicarbonate assay
I disagree that the problem is due to diffusion from open samples. Calibration with a primary standard (in our case sodium bicarbonate eliminates the difference between Abbott Architect and other analysers. When we first introduced the Architect results on patient samples were 3mmol/L lower than the Vitros analysers they replaced (samples analysed on Architect first).
Our samples are capped until they go on the track and are only decapped a few minutes before they reach the analyser spurs. Equilibrium with the air in the tube presumably occurs before the sample has been centrifuged. Old analysers typically sampled from the bottom of the sample cup but the sample cups tended to be uncapped in carousels or racks for some time before analysis. The Abbott low results are due only to standardisation.
Mike Collins
BMS3
Biochemistry Automation
Norfolk & Norwich University Hospital
England
[log in to unmask]
http://www.nnuh.nhs.uk/
------ACB discussion List Information--------
This is an open discussion list for the academic and clinical community working in clinical biochemistry.
Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content.
ACB Web Site
http://www.acb.org.uk
Green Laboratories Work
http://www.laboratorymedicine.nhs.uk
List Archives
http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
List Instructions (How to leave etc.)
http://www.jiscmail.ac.uk/
|