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Sean,
While I haven’t used the method on
a Beckman, we used to use the Trace Method on a
We found it to be a “delicate”
assay. Being based on porphyrins it is prone to ?Oxidation, which makes the
reagent layered, with different absorbances from top to bottom - so must be
mixed before each use to ensure acceptable precision. You should also try to keep
it as anaerobic as practical, this will extend the lige on board. (I don’t
know if Beckman provide straws or something similar to reduce air contact, but
these helped the Roche application.)
With a bit of care it can work OK, but
is not the greatest Lithium method around.
Regards
Greg
Greg Watts
Sydney Adventist Hospital Pathology
From:
Clinical biochemistry discussion list [mailto:[log in to unmask]]
On Behalf Of Sean Maguire
Sent: Saturday, 19 December 2009
12:46 AM
To:
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Subject: Trace Lithium on Beckman
DXs
Dear colleagues,
Could I get some help from Beckman users who have set up the
Trace Lithium reagent on the Beckman DX?
We set up the Thermo Infinity Lithium (Li 65 Synchron,
ref A19611, which is provided by Beckman in Beckman style
cartridges.
However 9 UKNEQAS samples (supplied kindly by UKNEQAS)
gave results about 0.1 less than the expected value.
A similar neg bias of 0.1 mmol/L was also seen
with about patient 30 samples. The flame assay gave expected results.
We then tried to set up the original Thermo Infinity Lithium
(ref TR56056) provided by Thermo Scientific as a user-defined one-shot
chemistry but this failed to calibrate this morning on the first go but we hope
to solve this.
There are 40 labs using Trace reagents and the UKNEQAS
results are good.
Is there something that we are missing?
Can I ask Beckmann users as to how they find
CVs on Lithium, how are external QC results and which kit exactly is
being used?
Any information on instrument settings used etc would be very
helpful.
Many thanks,
Sean Maguire,
Principal Biochemist,