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#21
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C13 to C12 Ratio of Natural and Synthetic Testosterone
Michael Press wrote:
In article , Geraard Spergen wrote: Michael Press wrote: In article , 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. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. What is photosynthesis if not a chemical reaction? At least make your beliefs consistent. I suggest you take up creationism. If that is not to your liking you will have to eat your beliefs, because we have known for many decades that chemical reaction rates for C12, C13, and C14 are different. Oh man, that's harsh! Differing chemical reaction rates cannot explain why plants have more C13 to begin with. You have to explain why C13 is more likely to become part of a plant than to become part of something else... or perhaps you could propose that flora C12 is more likely to absorb an itinerant neutron than fauna C12. Chemistry is mostly about electrons, photons are absorbed in the nucleus. I reasoned (perhaps incorrectly) that photosynthesis involves photons being absorbed by neutrons and that C13 had a higher cross section for photon absorption than did C12 and that this might account for plants having a higher proportion of C13 than non-photosynthesizing organisms. It may be a dumbass theory, but it can't hold a candle to creationism. But look, you are `reasoning' from your beliefs. Chemical reaction rates are also about mobility of reactants. That C13 is heavier than C12 affects its mobility. Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. For what it's worth, I have done mass spec measurements on isotopically labelled peptide mixtures (a much more complex sample than testosterone isolated from urine) and can say the devices have become exquisitely sensitive in the last 5 years, and they continue to double in sensitivity roughly every year. One can only hope that the lab is using recent state of the art to measure these samples. |
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#22
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C13 to C12 Ratio of Natural and Synthetic Testosterone
In article ,
Kyle Legate wrote: Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. Fine. Activation energy is increased by isotopic mass, reducing the reaction rate. And you state categorically, without anticipating any evidence to the contrary, that mobility has nothing to do with it. -- Michael Press |
#23
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C13 to C12 Ratio -- Is Floyd a Vegetarian?
Bob Dole wrote:
wrote: 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. [continued searching for possible Floyd excuse below] 1. What if you had been vegetarian for some relatively long period of time. Would this mean that the carbon entering your body had less 13C? Would this lead to your testosterone having less 13C? It would. However, this is why the "reference material" used is another endogenous steroid, not some testosterone taken off the shelf. (Those who perform studies using stable isotopically labeled tracers are exceedingly familiar with the need to obtain a baseline or background sample prior to tracer administration to account for the natural abundance of, e.g., 13C in whatever is being traced. The principle is the same here.) Andy Coggan |
#24
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C13 to C12 Ratio of Natural and Synthetic Testosterone
Kyle Legate wrote:
Michael Press wrote: Geraard Spergen wrote: Michael Press 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. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. What is photosynthesis if not a chemical reaction? At least make your beliefs consistent. I suggest you take up creationism. If that is not to your liking you will have to eat your beliefs, because we have known for many decades that chemical reaction rates for C12, C13, and C14 are different. Oh man, that's harsh! Differing chemical reaction rates cannot explain why plants have more C13 to begin with. You have to explain why C13 is more likely to become part of a plant than to become part of something else... or perhaps you could propose that flora C12 is more likely to absorb an itinerant neutron than fauna C12. Chemistry is mostly about electrons, photons are absorbed in the nucleus. I reasoned (perhaps incorrectly) that photosynthesis involves photons being absorbed by neutrons and that C13 had a higher cross section for photon absorption than did C12 and that this might account for plants having a higher proportion of C13 than non-photosynthesizing organisms. It may be a dumbass theory, but it can't hold a candle to creationism. But look, you are `reasoning' from your beliefs. Chemical reaction rates are also about mobility of reactants. That C13 is heavier than C12 affects its mobility. Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. For what it's worth, I have done mass spec measurements on isotopically labelled peptide mixtures (a much more complex sample than testosterone isolated from urine) and can say the devices have become exquisitely sensitive in the last 5 years, and they continue to double in sensitivity roughly every year. One can only hope that the lab is using recent state of the art to measure these samples. This is so great! I love tuning in to a TV show, say about bass fishing, and halfway through the program there's an in depth discussion about amine blush in fiberglass boat layup! R |
#25
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C13 to C12 Ratio of Natural and Synthetic Testosterone
-----BEGIN PGP SIGNED MESSAGE-----
In article .com, gds wrote: So, that pretty much is consistent with your desire for lots of folks to perfomr the test and see how accurate (reliable/valid) it is. - - That validates the test, but not the lab. No matter how good the science, the process needs to be validated. It's one thing to perform a test on a few samples with a potential publication pumping up your CV. It's a whole 'nother thing to do it on an industrial basis day after day. _ The lab in this case may be just fine, but real crime labs have to do this kind of validation, why not the WADA labs? An open process would have the results of this kind of testing publically available. It would be a fairly simple matter to include a few quality control samples in every batch. _ It's important to remember that once a bureacracy is formed it's primarly purpose is the continuation of the bureacracy. Regardless of what it's supposed to do, getting next year's funding is always job #1. WADA has a huge incentive to find cheats and zero incentive have a fair process. Unless getting next year's funding is dependent on passing such quality controls, their results will always be suspect. _ Booker C. Bense -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBRNITDWTWTAjn5N/lAQEzSQP/eqJ4vqm/7RNII/4SYEkk7Lr5JS+4AuFP k5uVw+GLM0J6t6LTLE4KxLZRk5pcSG1ynp9tqW4wj0bhgHVbag noZaDaf6dhKK2M xebkvT/kcRrcyAsuBAmLhJ8WXhV//EhvnrtB4HZZXiIhJhbAUagqEhDi8APeDbj0 zFLYer7mqSQ= =YmmY -----END PGP SIGNATURE----- |
#26
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C13 to C12 Ratio of Natural and Synthetic Testosterone
Kyle Legate wrote:
Michael Press wrote: In article , Geraard Spergen wrote: Michael Press wrote: In article , 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. Hard to believe there's any difference in chemical reactions, it's probably due to photosynthesis. What is photosynthesis if not a chemical reaction? At least make your beliefs consistent. I suggest you take up creationism. If that is not to your liking you will have to eat your beliefs, because we have known for many decades that chemical reaction rates for C12, C13, and C14 are different. Oh man, that's harsh! Differing chemical reaction rates cannot explain why plants have more C13 to begin with. You have to explain why C13 is more likely to become part of a plant than to become part of something else... or perhaps you could propose that flora C12 is more likely to absorb an itinerant neutron than fauna C12. Chemistry is mostly about electrons, photons are absorbed in the nucleus. I reasoned (perhaps incorrectly) that photosynthesis involves photons being absorbed by neutrons and that C13 had a higher cross section for photon absorption than did C12 and that this might account for plants having a higher proportion of C13 than non-photosynthesizing organisms. It may be a dumbass theory, but it can't hold a candle to creationism. But look, you are `reasoning' from your beliefs. Chemical reaction rates are also about mobility of reactants. That C13 is heavier than C12 affects its mobility. Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. And they have a higher activation energy because they vibrate differently for a given thermal energy level, in general the motion is slower and the vibrational excursions smaller. That is a "mobility" issue in the sense that the intermolecular atomic motion is less because the mass is greater and the overall energy at a given temperature is constant. So you have to give the system more energy to get the molecules vibrating enough to reach the activation threshold. Or maybe a better way to say it is that for a given Boltzman energy distribution, more lighter molecules will have enough energy to be above the activation threshold than heavier molecules. The fractionation across a gas-liquid interface is a translational mobility issue in general unless there is some sort of reaction going on along with the phase transition. In that case the diffusivity is roughly proportional to the mean molecular speed, which is a function of the molecular mass. Increase the mass, decrease the speed, decrease the diffusivity, decrease the flux across the gas-liquid boundary. Quantum tunneling (QT) can overcome some of the kinetic isotopic fractionation for hydrogen/deuterium but QT is also mass-dependent so there is also isotopic separation in this process as well. QT of heavier atoms has only been observed in a few weird systems that I know of but also would be subject to isotopic fractionation, though not to as large a degree as kinetic fractionation. -- Bill Asher |
#27
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C13 to C12 Ratio of Natural and Synthetic Testosterone
William Asher wrote:
Kyle Legate wrote: Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. And they have a higher activation energy because they vibrate differently for a given thermal energy level, in general the motion is slower and the vibrational excursions smaller. That is a "mobility" issue in the sense that the intermolecular atomic motion is less because the mass is greater and the overall energy at a given temperature is constant. Aha. When I saw mobility I thought you were referring to the rate of substrate delivery to enzyme active sites. Thinking like a biochemist, and not as a chemist. |
#28
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C13 to C12 Ratio of Natural and Synthetic Testosterone
Kyle Legate wrote:
William Asher wrote: Kyle Legate wrote: Mobility has nothing to do with it. Heavier isotopes have a higher activation energy, so they react slower. A phenomenon called hydrogen tunneling can overcome this but it is extremely rare. And they have a higher activation energy because they vibrate differently for a given thermal energy level, in general the motion is slower and the vibrational excursions smaller. That is a "mobility" issue in the sense that the intermolecular atomic motion is less because the mass is greater and the overall energy at a given temperature is constant. Aha. When I saw mobility I thought you were referring to the rate of substrate delivery to enzyme active sites. Thinking like a biochemist, and not as a chemist. I didn't define it quite correctly at first, I think. It's also confusing because there are two fractionation processes going on in plants, the first as CO2 goes across the stoma into the leaf, the second as the CO2 gets used to make sugar and cellulose and whatever. The first process is a true mobility effect, the second is the activation effect. -- Bill Asher |
#30
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C13 to C12 Ratio -- Is Floyd a Vegetarian?
wrote in message
ups.com... It would. However, this is why the "reference material" used is another endogenous steroid, not some testosterone taken off the shelf. (Those who perform studies using stable isotopically labeled tracers are exceedingly familiar with the need to obtain a baseline or background sample prior to tracer administration to account for the natural abundance of, e.g., 13C in whatever is being traced. The principle is the same here.) As I was saying Andy, using another steroid might not be a good idea. And the sample may have been poluted with other carbon sources that are more immediate than steroid production which is a great deal more detailed. So it is possible that there can be radically different ratios of C12/C13 in one component of urine and another component. |
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