This study was partially supported by a grant 18-05 from the Alzheimer&#8217;s Society of Canada (for A. K.) and Brain Canada Foundation with support from Health Canada. The authors would like to acknowledge the McGill University Faculty of Medicine, Montreal Neurological Institute and McConnell Brain Imaging Centre for support of this work. We also thank Mrs. Monica Lacatus-Samoila for help with quality control procedures and Drs. Jean-Paul Soucy and Gassan Massarweh for access to radioisotopes and the radiochemistry facility.

1. Preparation of buffers and eluents
<ol>
	<li>Dissolve 2.72 g of sodium acetate trihydrate in 100 mL of water to prepare 0.2 M sodium acetate solution (solution A).</li>
	<li>Dissolve 11.4 mL of glacial acetic acid in 1 L of water to prepare 0.2 M acetic acid solution (solution B).</li>
	<li>Combine 50 mL of solution A with 450 mL of solution B to prepare the acetate buffer at pH 3.7 (buffer 1) according to the buffer reference center15. Verify the pH of the buffer with pH strips or a pH meter...

<ol>
	<li>Langstrom, B., Lundqvist, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+preparation+of+11C-methyl+iodide+and+its+use+in+the+synthesis+of+11C-methyl-L-methionine.">The preparation of 11C-methyl iodide and its use in the synthesis of 11C-methyl-L-methionine.</a> The International journal of applied radiation and isotopes. 27 (7), 357-363 (1976).</li><li>Larsen, P., Ulin, J., Dahlstr&#248;m, K., Jensen, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+[11C]iodomethane+by+iodination+of+[11C]methane.">Synthesis of [11C]iodomethane by iodination of [11C]methane.</a> Applied radiation and isotopes. 48 (2), 153-157 (1997).</li><li>Jewett, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+synthesis+of+[11C]methyl+triflate.">A simple synthesis of [11C]methyl triflate.</a> International journal of radiation applications and instrumentation. Part A, Applied radiation and isotopes. 43 (11), 1383-1385 (1992).</li><li>Wilson, A. A., Garcia, A., Houle, S., Vasdev, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utility+of+commercial+radiosynthetic+modules+in+captive+solvent+[11C]-methylation+reactions.">Utility of commercial radiosynthetic modules in captive solvent [11C]-methylation reactions.</a> Journal of Labelled Compounds and Radiopharmaceuticals. 52 (11), 490-492 (2009).</li><li>Wilson, A. A., Garcia, A., Jin, L., Houle, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiotracer+synthesis+from+[(11)C]-iodomethane:+a+remarkably+simple+captive+solvent+method.">Radiotracer synthesis from [(11)C]-iodomethane: a remarkably simple captive solvent method.</a> Nuclear medicine and biology. 27 (6), 529-532 (2000).</li><li>Fedorova, O. S., Vaitekhovich, F. P., Krasikova, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+Synthesis+of+[18F]Fluoromethylcholine+for+Positron-Emission+Tomography+Imaging.">Automated Synthesis of [18F]Fluoromethylcholine for Positron-Emission Tomography Imaging.</a> Pharmaceutical Chemistry Journal. 52 (8), 730-734 (2018).</li><li>Jewett, D. M., Ehrenkaufer, R. L., Ram, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+captive+solvent+method+for+rapid+radiosynthesis:+application+to+the+synthesis+of+[1-(11)C]palmitic+acid.">A captive solvent method for rapid radiosynthesis: application to the synthesis of [1-(11)C]palmitic acid.</a> The International journal of applied radiation and isotopes. 36 (8), 672-674 (1985).</li><li>Watkins, G. L., Jewett, D. M., Mulholland, G. K., Kilbourn, M. R., Toorongian, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+captive+solvent+method+for+rapid+N-[11C]methylation+of+secondary+amides:+application+to+the+benzodiazepine,+4'-chlorodiazepam+(RO5-4864).">A captive solvent method for rapid N-[11C]methylation of secondary amides: application to the benzodiazepine, 4'-chlorodiazepam (RO5-4864).</a> International journal of radiation applications and instrumentation. Part A, Applied radiation and isotopes. 39 (5), 441-444 (1988).</li><li>Hockley, B. G., Henderson, B., Shao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+27,+Synthesis+of+{11C]Raclopride.">Chapter 27, Synthesis of {11C]Raclopride.</a> Radiochemical Syntheses. , 167-175 (2012).</li><li>Lodi, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+and+reproducibility+of+N-[11C]methyl-choline+and+L-(S-methyl-[11C])methionine+solid-phase+synthesis:+a+useful+and+suitable+method+in+clinical+practice.">Reliability and reproducibility of N-[11C]methyl-choline and L-(S-methyl-[11C])methionine solid-phase synthesis: a useful and suitable method in clinical practice.</a> Nuclear Medicine Communications. 29 (8), 736-740 (2008).</li><li>Jolly, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+"[(11)C]kits"+for+a+fast,+efficient+and+reliable+production+of+carbon-11+labeled+radiopharmaceuticals+for+Positron+Emission+Tomography.">Development of "[(11)C]kits" for a fast, efficient and reliable production of carbon-11 labeled radiopharmaceuticals for Positron Emission Tomography.</a> Applied radiation and isotopes. 121, 76-81 (2017).</li><li>Boudjemeline, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+efficient+solid+phase+supported+radiosynthesis+of+[(11)+C]PiB+using+tC18+cartridge+as+a+"3-in-1"+production+entity.">Highly efficient solid phase supported radiosynthesis of [(11) C]PiB using tC18 cartridge as a "3-in-1" production entity.</a> Journal of Labelled Compounds and Radiopharmaceuticals. 60 (14), 632-638 (2017).</li><li>Mathis, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+lipophilic+thioflavin-T+derivative+for+positron+emission+tomography+(PET)+imaging+of+amyloid+in+brain.">A lipophilic thioflavin-T derivative for positron emission tomography (PET) imaging of amyloid in brain.</a> Bioorganic and medicinal chemistry letters. 12 (3), 295-298 (2002).</li><li>Mathis, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+evaluation+of+11C-labeled+6-substituted+2-arylbenzothiazoles+as+amyloid+imaging+agents.">Synthesis and evaluation of 11C-labeled 6-substituted 2-arylbenzothiazoles as amyloid imaging agents.</a> Journal of medicinal chemistry. 46 (13), 2740-2754 (2003).</li><li>. Buffer Reference Center Available from: <a target="_blank" href="https://www.sigmaaldrich.com/life-science/core-bioreagents/biological-buffers/learning-center/buffer-reference-center.html">https://www.sigmaaldrich.com/life-science/core-bioreagents/biological-buffers/learning-center/buffer-reference-center.html</a> (2019)</li><li>Philippe, C., Mitterhauser, M., Wadsak, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+18,+Synthesis+of+2-(4-N-[11C]Methylaminophenyl)-6-Hydroxybenzothiazole+([11C]6-OH-BTA-1;+[11C]PIB).">Chapter 18, Synthesis of 2-(4-N-[11C]Methylaminophenyl)-6-Hydroxybenzothiazole ([11C]6-OH-BTA-1; [11C]PIB).</a> Radiochemical Syntheses. , 177-189 (2012).</li><li>Shao, X., Fawaz, M. V., Jang, K., Scott, P. J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Applications+of+[11C]Hydrogen+Cyanide.">Synthesis and Applications of [11C]Hydrogen Cyanide.</a> Radiochemical Syntheses. , 207-232 (2015).</li><li>Ametamey, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiosynthesis+and+preclinical+evaluation+of+11C-ABP688+as+a+probe+for+imaging+the+metabotropic+glutamate+receptor+subtype+5.">Radiosynthesis and preclinical evaluation of 11C-ABP688 as a probe for imaging the metabotropic glutamate receptor subtype 5.</a> Journal of Nuclear Medicine. 47 (4), 698-705 (2006).</li><li>Ametamey, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+PET+studies+of+metabotropic+glutamate+receptor+subtype+5+with+11C-ABP688.">Human PET studies of metabotropic glutamate receptor subtype 5 with 11C-ABP688.</a> Journal of Nuclear Medicine. 48 (2), 247-252 (2007).</li></ol>

Despite the recent emergence and FDA approval of several 18F-labeled PET tracers, such as florbetapir, florbetaben and flutemetamol, [11C]PiB remains a gold standard tracer for amyloid imaging due to the fast brain uptake and low non-specific binding. Currently this tracer is synthesized via either wet chemistry16 or using a &#34;dry loop&#34; approach4,17. Both methods require HPLC purification followed by r...

Positron emission tomography (PET) is a molecular imaging modality which relies on detecting the radioactive decay of an isotope attached to a biologically active molecule to enable the in vivo visualization of biochemical processes, signals and transformations. Carbon-11 (t1/2 = 20.3 min) is one of the most commonly used radioisotopes in PET because of its abundance in organic molecules and short half-life which allows for multiple tracer administrations on the same day to the same human or animal subject and reduces the radiation burden on the patients. Many tracers labeled with this isotope are used in clinical studies and in basic health research for in vivo PET imaging of classical and emerging biologically relevant targets - [11C]raclopride for D2/D3 receptors, [11C]PiB for amyloid plaques, [11C]PBR28 for translocator protein - to name just a few.
Carbon-11 labeled PET tracers are predominantly produced via 11C-methylation of non-radioactive precursors containing -OH (alcohol, phenol and carboxylic acid), -NH (amine and amide) or -SH (thiol) groups. Briefly, the isotope is generated in the gas target of a cyclotron via a 14N(p,&#945;)11C nuclear reaction in the chemical form of [11C]CO2. The latter is then converted into [11C]methyl iodide ([11C]CH3I) via either wet chemistry (reduction to [11C]CH3OH with LiAlH4 followed by quenching with HI)1 or dry chemistry (catalytic reduction to [11C]CH4 followed by radical iodination with molecular I2)2. [11C]CH3I can then be further converted to the more reactive 11C-methyl triflate ([11C]CH3OTf) by passing it over a silver triflate column3. The 11C-methylation is then performed by either bubbling the radioactive gas into a solution of non-radioactive precursor in organic solvent or via the more elegant captive solvent &#34;loop&#34; method4,5. The 11C-tracer is then purified by means of HPLC, reformulated in a biocompatible solvent, and passed through a sterile filter before being administered to human subjects. All of these manipulations must be fast and reliable given the short half-life of carbon-11. However, the use of an HPLC system significantly increases the losses of the tracer and production time, often necessitates the use of toxic solvents, complicates automation and occasionally leads to failed syntheses. Furthermore, the required cleaning of the reactors and HPLC column prolongs delays between the syntheses of subsequent tracer batches and increases the exposure of personnel to radiation.
The radiochemistry of fluorine-18 (t1/2 = 109.7 min), the other widely used PET isotope, has been recently advanced via the development of cassette-based kits that obviate the need for HPLC purification. By employing solid phase extraction (SPE) cartridges, these fully disposable kits allow for the reliable routine production of 18F-tracers, including [18F]FDG, [18F]FMISO, [18F]FMC and others, with shorter synthesis times, reduced personnel involvement and minimal maintenance of the equipment. One of the reasons carbon-11 remains a less popular isotope in PET imaging is a lack of similar kits for the routine production of 11C-tracers. Their development would significantly improve synthetic reliability, increase radiochemical yields and simplify automation and preventive maintenance of the production modules.
Currently available production kits take advantage of inexpensive, disposable, SPE cartridges instead of HPLC columns for the separation of the radiotracer from unreacted radioactive isotope, precursor and other radioactive and non-radioactive by-products. Ideally, the radiolabeling reaction also proceeds on the same cartridge; for example, the [18F]fluoromethylation of dimethylaminoethanol with gaseous [18F]CH2BrF in the production of prostate cancer imaging PET tracer [18F]fluoromethylcholine occurs on a cation-exchange resin cartridge6. Although similar procedures for the radiolabeling of several 11C-tracers on cartridges have been reported7,8 and became especially powerful for the radiosynthesis of [11C]choline9 and [11C]methionine10, these examples remain limited to oncological PET tracers where the separation from the precursor is often not required. We recently reported the development of &#34;[11C]kits&#34; for the production of [11C]CH3I11 and subsequent 11C-methylation, as well as solid phase-supported synthesis12 in our endeavours to simplify the routine production of 11C-tracers. Here, we wish to demonstrate our progress using the example of the solid phase supported radiosynthesis of [11C]PiB, a radiotracer for A&#946; imaging which revolutionized the field of Alzheimer&#39;s disease (AD) imaging when it was first developed in 2003 (Figure 1)13,14. In this method, volatile [11C]CH3OTf (bp 100 &#176;C) is passed over 6-OH-BTA-0 precursor deposited on the resin of a disposable cartridge. PET tracer [11C]PiB is then separated from the precursor and radioactive impurities by elution from the cartridge with biocompatible aqueous ethanol. Further, we automated this method of [11C]PiB radiosynthesis using a remotely operated radiochemistry synthesis module and disposable cassette kits. Specifically, we implemented this radiosynthesis on a 20-valve radiochemistry module, equipped with syringe drive (dispenser) which fits standard 20 mL disposable plastic syringe, gas flow controller, vacuum pump and gauge. Due to the simplicity of this method, we are confident that it can be modified to most commercially available automated synthesizers, either cassette-based or those equipped with stationary valves. This solid phase supported technique facilitates [11C]PiB production compliant with Good Manufacturing Practice (GMP) regulations and improves synthesis reliability. The technique described here also reduces the amount of precursor required for radiosynthesis, uses only &#34;green&#34; biocompatible solvents and decreases the time between consecutive production batches.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>6-OH-BTA-0</td>
			<td>ABX advanced biochemical compounds</td>
			<td>5101</td>
			<td>Non-radioactive precursor of [11C]PiB</td>
		</tr>
		<tr>
			<td>6-OH-BTA-1</td>
			<td>ABX advanced biochemical compounds</td>
			<td>5140</td>
			<td>Non-radioactive standard of [11C]PiB</td>
		</tr>
		<tr>
			<td>Agilent 1200 HPLC system</td>
			<td>Agilent</td>
			<td>Agilent 1200</td>
			<td>Analytical HPLC system</td>
		</tr>
		<tr>
			<td>Ethanol absolute</td>
			<td>Commercial alcohols</td>
			<td>432526</td>
			<td></td>
		</tr>
		<tr>
			<td>Hamilton syringe (luer-tip, 250 &#181;L)</td>
			<td>Hamilton</td>
			<td>HAM80701</td>
			<td></td>
		</tr>
		<tr>
			<td>MZ Analytical PerfectSil 120</td>
			<td>MZ-Analysentechik GmbH</td>
			<td>MZ1440-100040</td>
			<td>Analytical HPLC column</td>
		</tr>
		<tr>
			<td>Perkin Elmer Clarus 480 GC system</td>
			<td>Perkin Elmer</td>
			<td>Clarus 480</td>
			<td>Gas chromotograph</td>
		</tr>
		<tr>
			<td>polycarbonate manifold</td>
			<td>Scintomics</td>
			<td>ACC-101</td>
			<td>Synthesis manifold</td>
		</tr>
		<tr>
			<td>Restek MTX-Wax column (30 m, 0.53 mm)</td>
			<td>Restek</td>
			<td>70625-273</td>
			<td>Analytical GC column</td>
		</tr>
		<tr>
			<td>Scintomics GRP module</td>
			<td>Scintomics</td>
			<td>Scintomics GRP</td>
			<td>Automated synthesis unit</td>
		</tr>
		<tr>
			<td>Sep-Pak tC18 Plus</td>
			<td>Waters</td>
			<td>WAT020515</td>
			<td>Solid phase extraction cartridge</td>
		</tr>
		<tr>
			<td>solvent-resistant manifold</td>
			<td>Scintomics</td>
			<td>ACC-201</td>
			<td>Synthesis manifold</td>
		</tr>
		<tr>
			<td>Spinal needle</td>
			<td>BD</td>
			<td>405181</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile extension line</td>
			<td>B. Braun</td>
			<td>8255059</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile filter</td>
			<td>Millipore</td>
			<td>SLLG013SL</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile vial (20mL)</td>
			<td>Huayi</td>
			<td>SVV-20A</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile water</td>
			<td>Baxter</td>
			<td>JF7623</td>
			<td></td>
		</tr>
		<tr>
			<td>Synthra MeIplus Research</td>
			<td>Synthra</td>
			<td>MeIplus Research</td>
			<td>[11C]CH3I/[11C]CH3OTf module</td>
		</tr>
		<tr>
			<td>Syringe (10 mL)</td>
			<td>BD</td>
			<td>309604</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe (1mL)</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe (20 mL)</td>
			<td>B. Braun</td>
			<td>4617207V</td>
			<td>Dispenser syringe</td>
		</tr>
		<tr>
			<td>Vent filter</td>
			<td>Millipore</td>
			<td>TEFG02525</td>
			<td></td>
		</tr>
	</tbody>
</table>

solid phase 11c-methylation, purification and formulation for the production of pet tracers

Routine production of radiotracers used in positron emission tomography (PET) mostly relies on wet chemistry where the radioactive synthon reacts with a non-radioactive precursor in solution. This approach necessitates purification of the tracer by high performance liquid chromatography (HPLC) followed by reformulation in a biocompatible solvent for human administration. We recently developed a novel 11C-methylation approach for the highly efficient synthesis of carbon-11 labeled PET radiopharmaceuticals, taking advantage of solid phase cartridges as disposable &#34;3-in-1&#34; units for the synthesis, purification and reformulation of the tracers. This approach obviates the use of preparative HPLC and reduces the losses of the tracer in transfer lines and due to radioactive decay. Furthermore, the cartridge-based technique improves synthesis reliability, simplifies the automation process and facilitates compliance with the Good Manufacturing Practice (GMP) requirements. Here, we demonstrate this technique on the example of production of a PET tracer Pittsburgh compound B ([11C]PiB), a gold standard in vivo imaging agent for amyloid plaques in the human brains.

To summarize a typical radiosynthesis of [11C]PiB, gaseous [11C]CH3OTf is first passed through a tC18 cartridge preloaded with a solution of precursor (Figure 1). Separation of the reaction mixture is then achieved by successive elution with aqueous ethanol solutions as follows. First, 12.5% EtOH elutes the majority of unreacted [11C]CH3OTf and 6-OH-BTA-0, then 15% EtOH washes out the residual impurities,...

Watch this Scientific Journal Video about Solid Phase 11C-Methylation, Purification and Formulation for the Production of PET Tracers at JoVE.com

Solid Phase 11C-Methylation, Purification and Formulation for the Production of PET Tracers

We report an efficient carbon-11 radiolabeling technique to produce clinically relevant tracers for Positron Emission Tomography (PET) using solid phase extraction cartridges. 11C-methylating agent is passed through a cartridge preloaded with precursor and successive elution with aqueous ethanol provides chemically and radiochemically pure PET tracers in high radiochemical yields.

Solid Phase 11C-Methylation, Purification and Formulation for the Production of PET Tracers

Routine production of radiotracers used in positron emission tomography (PET) mostly relies on wet chemistry where the radioactive synthon reacts with a ...

Carbon-11 is one of the most widely used radioisotopes in positron emission tomography because of its abundance in organic molecules and a short half-life of 20 minutes. In this video, we show an efficient carbon-11 radiolabeling technique using solid-phase extraction cartridges. Compared to conventional methods, cartridge-based techniques obviates the use of HPLC, shortens the radiosynthesis time, improves synthesis reliability, simplifies automation process, and facilitates compliance with the Good Manufacturing Practices, GMP.The cartridge-based technique is demonstrated here on the radiosynthesis of C11 PiB, a PET tracer used for the in vivo imaging of amyloid plaques in the brains of patients suffering from Alzheimer's disease. Recently, we applied the three-in-one technique to the radiosynthesis of C11 ABP688, a PET tracer for the imaging of metabotropic glutamate receptors type five, as well as other carbon-11 labeled tracers. Combine 450 milliliters of 0.2-molar solution of acetic acid with 50 milliliters of 0.2-molar solution of sodium acetate to prepare the acetate buffer at pH 3.7 as buffer one.Verify the pH of the buffer with pH strips or a pH meter. Then, combine 12.5 milliliters of absolute ethanol with 87.5 milliliters of acetate buffer in a 100-milliliter bottle to make 12.5%aqueous ethanol solution as wash one. Combine 15 milliliters of absolute ethanol with 85 milliliters of acetate buffer in a 100-milliliter bottle to make 15%aqueous ethanol solution as wash two.Combine five milliliters of absolute ethanol with five milliliters of acetate buffer to make 50%aqueous ethanol solution as final eluent, and draw 2.5 milliliters of this solution into a 10-milliliter syringe. To precondition the tC18 cartridge, from the female end, use a syringe to pass 10 milliliters of water followed by five milliliters of acetone through the cartridge. Dry the cartridge with a stream of nitrogen at 50 milliliters per minute for one minute.In an Eppendorf tube, dissolve two milligrams of the precursor 6-OH-BTA-0 in one milliliter of anhydrous acetone. Holding a Luer-tip, 250-microliter, precision glass syringe downwards, withdraw 100 microliters of the precursor solution and then 50 microliters of air cushion. Remove the needle, and tap the syringe to make sure the air cushion is above the solution in a syringe.Apply the precursor solution to the tC18 cartridge from the female end by slowly pushing the plunger all the way down. Do not push the air any further. Secure and assemble the standard five-port disposable manifold on the synthesis module.Port one has two positions. Connect the horizontal inlet to the automated dispenser fitted with a 20-milliliter syringe. Connect the vertical inlet to the bottle with wash one.Connect the output of the module which produces C11 methyl triflate to port two of the manifold. Install the tC18 cartridge loaded with precursor 6-OH-BTA-0 between ports three and four. Port five has two positions.Connect the horizontal outlet to the waste bottle and the vertical outlet to the sterile vial for tracer collection via the sterile filter. In the lead-shielded hot cell, use a Teflon line to deliver C11 methyl triflate into the manifold through port two, and pass it through the loaded tC18 cartridge at 20 milliliters per minute output flow. The C11 methyl triflate module regulates the flow via ports three and four and into the waste bottle.Once all the radioactivity has been transferred and trapped in the tC18 cartridge as monitored by the radioactivity detector, stop the flow of gas by closing port two. Let the cartridge sit for two minutes to complete the reaction. Then, through port one, withdraw 19 milliliters of wash one solution from the 100-milliliter bottle into the dispenser syringe at 100 milliliters per minute.Dispense 18.5 milliliters of wash one solution from the dispenser through the tC18 cartridge via ports three and four and into the waste bottle at 50 milliliters per minute. Ensure the absence of air bubbles in the manifold, as they might diminish the separation efficiency. Repeat the withdrawing and dispensing four times with 18.5 milliliters of wash one solution each time and a total volume of 92.5 milliliters passing through tC18.Switch the input line on port one from wash one to wash two. Repeat the withdrawing and dispensing three times with 18.5 milliliters of wash two solution each time and total volume of 55.5 milliliters passing through tC18. Toggle valve five towards the final vial.Disconnect the line from the dispenser, and connect it to the 10-milliliter syringe containing 2.5 milliliters of the final eluent solution and 7.5 milliliters of air. Holding the syringe downwards, manually push the final eluent solution followed by the air through the tC18 cartridge via ports three and four and into the sterile vial for tracer collection via the sterile filter. Switch the syringe to the one containing 10 milliliters of the sterile phosphate buffer, and push the entire volume through the tC18 cartridge into the sterile vial.Disconnect the syringe, and flush the line with 10 milliliters of air using the same syringe. Using one-milliliter syringe, withdraw samples for prerelease quality control procedures, bacterial endotoxin test, and sterility test. To perform prerelease quality control procedures, first determine the radiochemical identity, radiochemical purity, chemical purity, and molar activity of the tracer by an analytical HPLC system equipped with UV radioactivity detectors and a reversed-phase column.Determine the retention times of 6-OH-BTA-0 and 6-OH-BTA-1, and calibrate the instrument to quantify the content of each compound. Determine the residual solvent content by the analytical gas chromatography system equipped with a capillary column. Determine the retention times of acetone and ethanol, and calibrate the instrument to quantify the content of each solvent.This study performed the radiosynthesis of C11 PiB by C11-methylation of 6-OH-BTA-0 precursor with C11 methyl triflate. Quality control analytical HPLC of C11 PiB shows the radiochemical purity was 98%The retention times of 6-OH-BTA-0 precursor and 6-OH-BTA-1 tracer peak on the UV chromatogram were 3.6 and 5.9 minutes, respectively. The analysis of the UV trace shows residual precursor concentration below the acceptable limit of 1.3 micrograms in the absence of other non-radioactive impurities.This indicates the radiochemical and chemical purity of the tracer is acceptable for clinical PET studies. Increasing the 6-OH-BTA-0 precursor amount from 0.1 milligrams to 0.3 milligrams improved the radiochemical yield from 18.1%to 32.1%at the expense of a slightly higher amount of the precursor in the final product. This technique should be applicable to many different systems with a suitable difference in polarity between the precursor and radiolabeled product.All manipulations involving radioactive isotopes must be performed in a lead-shielded hot cell by personnel with adequate training to handle radioactive materials.

solid-phase-11c-methylation-purification-formulation-for-production

Research

JoVE Journal

Chemistry

6.5K visualizações.  McGill University. O carbono-11 é um dos radioisótopos mais utilizados na tomografia de emissão de pósitrons devido à sua abundância em moléculas orgânicas e uma curta meia-vida de 20 minutos. Neste vídeo, mostramos uma técnica eficiente de rotulagem de radiolabeling de carbono-11 usando cartuchos de extração em fase sólida. Em comparação com os métodos convencionais, as técnicas baseadas em cartuchos evitam o uso do HPLC, encurtam o tempo de radiosíntese, melhoram a confiabilidade da síntese...