RE: Calibrating Across Continents

ALT Service (Tony Leger) wrote:
>To All,
>I feel this topic very important.
>
>This reply is not intended as a solicitation, rather to share and check the
>experience I have gained.
>
>I agree with Robert on most points totally. In my experience, instrument
>stability is a direct result of instrument maintenance.  A higher level of
>maintenance will give a more stable instrument. Like Robert, I suspect from
>the operation description given by Russ, many instruments are not operating
>at optimum levels and a few are probably not even operating at acceptable
>levels, but what can you say, FACScomp passed anyway.
>
>In my opinion, A good QA procedure should include both an instrument control
>and an assay control as well as concerns for flow rates and CV's at a
>minimum.
>
>Concerning the issue of calibration. According to GMP(Good Manufacturing
>Practices), when using the term calibration in the US, one should understand
>the implication that a standard exists which is traceable to NIST. Such is
>the case with size, weight or electronic standards, etc.. For example, when
>we have our test equipment, scales & thermometers, etc. calibrated they are
>compared to a standard which is traceable to NIST. A report and a sticker
>are provided to indicate and verify such traceability. To my knowledge, no
>traceable standard exists for fluorescence emissions. MESF values can be
>helpful, but not traceable to NIST.
>
> From a regulatory stand point, how can we calibrate a flow cytometer when no
>traceable standard exists to compare readings to?
>Technically, I believe we can't.


To make a long story short, see:

http://ts.nist.gov/ts/htdocs/230/232/QUARTERLY/September2004%20Spotlight.pdf

Adolfas Gaigalas et al at NIST have developed fluorescein-labeled beads as 
a Standard Reference Material that can be used by bead manufacturers to 
assign NIST-traceable MESF values to secondary standard beads.

-Howard