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C13 to C12 Ratio of Natural and Synthetic Testosterone
Maybe this belongs in rec.bicycles.racing.chemistry.organic.synthesis.
From what I've been reading, the isotope ratio of synthetic testosterone is only somewhat different than that of natural testosterone. Does anyone know how much the difference is? And better yet, why is there a difference? I am assuming that all carbon in the biosphere has the same C12/C13 ratio, and that the difference in masses is unlikely to produce any kinetic differences during the biosynthetic reactions, in stark contrast to H1/H2 isotopes. Is it that a starting material is taken from the soy source and then modified with petroleum derived reagents (which have no C13 since they have been in the ground for millenia)? John Aspen Research, - www.aspenresearch.com "Turning Questions into Answers" Opinions expressed herein are my own and may not represent those of my employer. |
C13 to C12 Ratio of Natural and Synthetic Testosterone
"Dumbass" wrote in news:1154526076.715933.152870@
75g2000cwc.googlegroups.com: I think they must be using C14. C14 is created in the atmosphere by cosmic rays. When it get sequestered in petroleum buried and safe from cosmic rays, it decays. So testosterone of biological origin has higher C14 than petroleum-derived. As I understand they use the stable isotopes 13C and 12C, referenced to a standard 13C/12C value as measured from some kind of belemnite apparently. The fractionation occurs because of different chemical reactions or reaction speeds in plants and animals to make the testosterone; 12C reacts slightly more easily and a fast reaction will result in testosterone relatively enriched with 12C. |
C13 to C12 Ratio of Natural and Synthetic Testosterone
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C13 to C12 Ratio of Natural and Synthetic Testosterone
wrote: wrote: Maybe this belongs in rec.bicycles.racing.chemistry.organic.synthesis. From what I've been reading, the isotope ratio of synthetic testosterone is only somewhat different than that of natural testosterone. Does anyone know how much the difference is? And better yet, why is there a difference? I am assuming that all carbon in the biosphere has the same C12/C13 ratio, and that the difference in masses is unlikely to produce any kinetic differences during the biosynthetic reactions, in stark contrast to H1/H2 isotopes. Is it that a starting material is taken from the soy source and then modified with petroleum derived reagents (which have no C13 since they have been in the ground for millenia)? The difference is small (~3 parts per thousand PDB), but readily measurable if you've got good technique. It arise from the fact that synthetic testosterone is produced from plant sterols, which are lower in 13C than animal hormones/tissues/etc. due to isotopic discrimination. Andy Coggan This isotope test are very difficult. The manufacturer of the testing equiptment says "quite regularly there are errors." http://online.wsj.com/public/article... main_tff_top Someone should question the UCI use of the equiptment for IRMS. The article concludes: "The apparent sensitivity of the testosterone test's numbers to alcohol consumption, and the announcement of partial test results without full disclosure by the cycling union, has created a milieu for cyclists that is "almost Kafka-esque," Dr. Davis said. "The phrase often bandied about is 'chemical McCarthyism'."" |
C13 to C12 Ratio of Natural and Synthetic Testosterone
Jonathan v.d. Sluis wrote:
"Dumbass" wrote in news:1154526076.715933.152870@ 75g2000cwc.googlegroups.com: I think they must be using C14. C14 is created in the atmosphere by cosmic rays. When it get sequestered in petroleum buried and safe from cosmic rays, it decays. So testosterone of biological origin has higher C14 than petroleum-derived. As I understand they use the stable isotopes 13C and 12C, referenced to a standard 13C/12C value as measured from some kind of belemnite apparently. The fractionation occurs because of different chemical reactions or reaction speeds in plants and animals to make the testosterone; 12C reacts slightly more easily and a fast reaction will result in testosterone relatively enriched with 12C. C12 is 99% of all carbon, C13 is 1%, and C14 is about 1 part per 10^12. Plants naturally have more C13 than animals so any substance (including testosterone) produced from plants will have a higher C13 proportion than the same substance produced by animals. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. |
C13 to C12 Ratio of Natural and Synthetic Testosterone
Geraard Spergen wrote:
C12 is 99% of all carbon, C13 is 1%, and C14 is about 1 part per 10^12. Plants naturally have more C13 than animals so any substance (including testosterone) produced from plants will have a higher C13 proportion than the same substance produced by animals. Nice explanation. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. Um, isn't photosynthesis a chemical reaction? ;-) Andy Coggan |
C13 to C12 Ratio of Natural and Synthetic Testosterone
|
C13 to C12 Ratio of Natural and Synthetic Testosterone
Geraard Spergen wrote:
wrote: Geraard Spergen wrote: C12 is 99% of all carbon, C13 is 1%, and C14 is about 1 part per 10^12. Plants naturally have more C13 than animals so any substance (including testosterone) produced from plants will have a higher C13 proportion than the same substance produced by animals. Nice explanation. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. Um, isn't photosynthesis a chemical reaction? ;-) Andy Coggan It's a photo-chemical reaction, maybe instead of "probably" I should have said "my wild-ass guess" Fractionation also occurs in non-photochemical processes such as bacterial respiration in deep smoker vents. It's more related to the difference in diffusivity of CO2 (or bicarbonate) containing heavier carbon isotopes, the heavier things move around slower. You also get fractionation in exchange of CO2 across the air-sea boundary (a mainly diffusive process) but not so much in precipitation of carbonate, where diffusion is not so important. -- Bill Asher |
C13 to C12 Ratio of Natural and Synthetic Testosterone
wrote: wrote: wrote: Maybe this belongs in rec.bicycles.racing.chemistry.organic.synthesis. From what I've been reading, the isotope ratio of synthetic testosterone is only somewhat different than that of natural testosterone. Does anyone know how much the difference is? And better yet, why is there a difference? I am assuming that all carbon in the biosphere has the same C12/C13 ratio, and that the difference in masses is unlikely to produce any kinetic differences during the biosynthetic reactions, in stark contrast to H1/H2 isotopes. Is it that a starting material is taken from the soy source and then modified with petroleum derived reagents (which have no C13 since they have been in the ground for millenia)? The difference is small (~3 parts per thousand PDB), but readily measurable if you've got good technique. It arise from the fact that synthetic testosterone is produced from plant sterols, which are lower in 13C than animal hormones/tissues/etc. due to isotopic discrimination. Andy Coggan This isotope test are very difficult. The manufacturer of the testing equiptment says "quite regularly there are errors." http://online.wsj.com/public/article... main_tff_top Someone should question the UCI use of the equiptment for IRMS. The article concludes: "The apparent sensitivity of the testosterone test's numbers to alcohol consumption, and the announcement of partial test results without full disclosure by the cycling union, has created a milieu for cyclists that is "almost Kafka-esque," Dr. Davis said. "The phrase often bandied about is 'chemical McCarthyism'."" True, it is 'chemical McCarthyism'. But, in this case there is a commie under every just about every bed. There is a lot of doping below the detection limits, IMO. Justified paranoia. |
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