What Shackleton Did
In "Idiots look at Data", we wondered what Shackleton did to be sure he was looking at the right thing. The answer seems to be on GDC 1100. We learn that he did the GCMS at one site, then shipped the samples to another site, not unlike the two machine setup at LNDD over a longer distance.
Confirmation of identity of steroids in extracts.It is not clear to us from reading this if impact MS data were acquired and analyzed at the GC/C/IRMS site, or only from the GC/MS site.
Prior to sending the first samples for GC/C/IRMS analyses in England, the identities of the principal components of the chromatogram were confirmed by GC/MS. This was carries out on a Hewlett-Packard 5970 instrument housing a 15 meter DB1 capillary column. The peaks chosen for GC/C/IRMS analyses had retention times and electrion impact mass spectra identical to those of 5a- and 5b-androstanediol diacetate and pregnanediol diacetate. Reference steroid for these compounds were also analyszed on the GC/C/IRMS instrument using both DB1 and DB17 columns, and these gave identical retention times to the urinary steroids. Pregnanetriol could also be analyzed by GC/C/IRMS.
I'm not smart enough to tell if Shackleton's chemistry is the same as what we know of LNDD's.
4 comments:
Identical retention times are stated twice in this quote. I expect that means it exceeds the '1%' criteria.
To me this would be expected of properly calibrated, operated and linearity verified machines, using the same temp ramp, etc (chromatographic conditions).
Step back and compare the clarity of this writeup with the mess from LNDD.
Duckstrap here. The fact that they are looking at the diacetates of the metabolites means that they did something essentially the same as LNDD. In the LNDD procedure, the samples were exposed to acetic anhydride which adds an acetate everywhere there is a hydroxyl group in the parent molecule. For the testosterone metabolites, this is 2 per molecule; hence the diacetates.
Thanks, Duck.
That still leaves us with a question. If LNDD did what Shackleton did, why are their chromatograms so much dirtier than his?
More stuff in the sample, or something else done different at the chromatographic level?
Remember, Shackleton had dopers in the sample group, so saying the 'stuff' in the LNDD CG's was the testosterone doping doesn't answer the question.
TBV
TbV,
The difference may lie in differences in the sample clean-up procedure. As I recall, LNDD goes through two liquid-solid extraction steps to generate F1, F2 and F3, whose purpose is to remove excess junk from the urine sample.
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