Dr. Chin,
I asked our PBB/PBDE expert Dr. Michele Schantz about your
question. Dr. Schantz is the technical contact for SRM 2585, Organic
Contaminants in House Dust, which is certified for 15 PBDE congeners
with reference and information values for 9 additional congeners. I
believe her team is developing a solution SRM designed to contain
suites of PBB and PBDE congeners. I don't know the schedule, but
they are moving fast to be able to collaborate with IRMM on BFRs in plastics.
Regarding your question, Dr. Schantz said "It depends on the
ionization source being used in the MS (mass spectrometer) too. For
electron impact (EI) MS, one will see larger differences in the
response factors from the different congeners than one would see if
using negative chemical ionization (NCI) MS. One can use the 20
congeners to quantify more or total, but there will obviously be
smaller errors as one increases the number of congeners used (to calibrate)."
At this time, we know of one source of commercial reference
materials. Accustandard has 160+ PBDE congeners and 22 PBB congeners
available. We invite our LF participants to inform us if they know
of additional sources of reference materials.
My (nonexpert) take on this is that you need to calibrate response
factors by either direct calibration or by estimation through
interpolation or extrapolation. On the uncertainty
considerations, you can do a reasonable job with fewer congeners,
but if you really want to get the lowest overall uncertainty, you
need more congeners in your reference material(s). Either way, the
lab must estimate of the uncertainty of their results in a realistic manner.
Hope this helps!
John Sieber
At 11:58 PM 5/23/2006, Clavius Chin wrote:
> Recently I approached and surveyed an ISO 17025 certified
>commerical lab, and they told me that in their GCMS analysis of TOTAL
>concentration of PBB & PBDE, they use only 10 PBB & 10 PBDE Calibration
>Standards, instead of the full 209 PBB & 208 PBDE (Deca-BDE is exempted)
>standards for their calibration. I'm quite shocked by their reply. I think
>this is wrong because what this commerical lab can actually report is only
>the concentration of these 10 PBB & 10 PBDE congeners, but not the TOTAL
>concentration as required by the EU, right? Shouldn't this commerical lab
>uses more calibration standards?
>
> Does anyone knows exactly how many PBB/PBDE congeners are
>available commerically and point me to the right source? Currently my RoHS
>lab has already acquired some (certainly more than 10) PBB & PBDE
>calibration standards for my GCMS, and is still sourcing for more.
>
>
>
>Best Regards,
>Clavius Chin, Ph.D.
>Failure Analysis & Lab Manager
>
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John R. Sieber, PhD
Research Chemist
National Institute of Standards and Technology
Chemical Science and Technology Laboratory
Analytical Chemistry Division
100 Bureau Drive, Stop 8391
Gaithersburg, MD 20899-8391 USA
[log in to unmask]
Tel: 1.301.975.3920
Fax: 1.301.869.0413
www.cstl.nist.gov/
Identification of commercial items in this document does
not imply endorsement by NIST or that items are
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