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Testosterone Replacement, Low T, HCG, & Beyond
Blood Test Discussion
Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods
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<blockquote data-quote="madman" data-source="post: 260323" data-attributes="member: 13851"><p><strong><em>*Size-exclusion separation (SES; also known as gel filtration chromatography) is another technique that may be used for separation of FH from biological samples.</em></strong></p><p><strong><em></em></strong></p><p><strong><em>*Because of the complexity of SES separations and relatively low efficiency of the SES using packed chromatographic columns, no online SES-based methods for small MW FH, intended for routine use, have been developed so far.</em></strong></p><p><strong><em></em></strong></p><p><strong><em>*The main difference between FH separation using SES adsorbents vs UF and ED devices is that in ED and UF devices separation takes place on a surface of the porous membrane, while in the SES devices separation of FH occurs within a system of pores, having a thousands-of-times greater surface area compared to the linear surface of UF and ED membranes.</em></strong></p><p></p><p><em><strong>* <u>Use of offline SES devices for separation of FH from biological samples (91) provides a number of advantages over ED and UF including the following</u>: (a) fast, within-minutes separation of FH from biological samples; (b) the fast separation prevents reestablishing equilibrium between the protein-bound hormone and the FH during the separation process, as occurs during the multihour ED separations, which can result in new portions of FH being released from the carrier protein while FH is transferred from the sample across the ED membrane into the dialysis buffer; (c) consistent performance over a wide range of protein concentrations in the biological samples (the system of pores within the particles does not get clogged as happens in the membrane of the UF devices); (d) ability to process samples in native conditions without disturbing the FH binding to their carrier proteins; (e) because of these issues, the observed FH concentrations more accurately reflect the true FH concentration in the biological samples; (f) the devices enable separation of FH that are unstable in dialysis buffer (e.g., F25OHD2/D3) or tend to adsorb to the surfaces (86, 87, 91, 101); and (g) the offline-SES devices are available in a 96-well format allowing batch sample processing. Use of these devices was recently demonstrated for analysis of F25OHD2/D3 and FTe (86, 87, 91, 101)</strong></em></p></blockquote><p></p>
[QUOTE="madman, post: 260323, member: 13851"] [B][I]*Size-exclusion separation (SES; also known as gel filtration chromatography) is another technique that may be used for separation of FH from biological samples. *Because of the complexity of SES separations and relatively low efficiency of the SES using packed chromatographic columns, no online SES-based methods for small MW FH, intended for routine use, have been developed so far. *The main difference between FH separation using SES adsorbents vs UF and ED devices is that in ED and UF devices separation takes place on a surface of the porous membrane, while in the SES devices separation of FH occurs within a system of pores, having a thousands-of-times greater surface area compared to the linear surface of UF and ED membranes.[/I][/B] [I][B]* [U]Use of offline SES devices for separation of FH from biological samples (91) provides a number of advantages over ED and UF including the following[/U]: (a) fast, within-minutes separation of FH from biological samples; (b) the fast separation prevents reestablishing equilibrium between the protein-bound hormone and the FH during the separation process, as occurs during the multihour ED separations, which can result in new portions of FH being released from the carrier protein while FH is transferred from the sample across the ED membrane into the dialysis buffer; (c) consistent performance over a wide range of protein concentrations in the biological samples (the system of pores within the particles does not get clogged as happens in the membrane of the UF devices); (d) ability to process samples in native conditions without disturbing the FH binding to their carrier proteins; (e) because of these issues, the observed FH concentrations more accurately reflect the true FH concentration in the biological samples; (f) the devices enable separation of FH that are unstable in dialysis buffer (e.g., F25OHD2/D3) or tend to adsorb to the surfaces (86, 87, 91, 101); and (g) the offline-SES devices are available in a 96-well format allowing batch sample processing. Use of these devices was recently demonstrated for analysis of F25OHD2/D3 and FTe (86, 87, 91, 101)[/B][/I] [/QUOTE]
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Testosterone Replacement, Low T, HCG, & Beyond
Blood Test Discussion
Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods
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