On-line ["Clmethylation using ["Clmethyl iodide has been successfully applied to the preparation of L-[methyl-"Clmethionine ("C-Met). ["C]Methyl iodide is first trapped in a short column that contains Porapak Q and L-homocysteine thiolactone coated on inert support. The column is then charged with N
Measurement of l-[methyl-11C]methionine in human plasma
✍ Scribed by Kiichi Ishiwata; Motonobu Kameyama; Jun Hatazawa; Kazuo Kubota; Tatsuo Ido
- Publisher
- Elsevier Science
- Year
- 1991
- Weight
- 249 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0883-2889
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✦ Synopsis
The routine measurement of L-[methyl-11C]methionine in human plasma after i.v. injection of the tracer is described. The protein-free plasma metabolites of the tracer were analyzed using a cation-exchange column (Aminex A-6) eluted with a pH 4.25 citrate buffer. The ratios of L-[methyl-11C]methionine for the total radioactivity decreased gradually, and the standard deviations among 19 humans were relatively small for 30 min: 97.2 +/- 1.4%, 5 min; 92.6 +/- 2.1%, 10 min; 89.4 +/- 4.0%, 15 min; 84.1 +/- 3.1%, 20 min; 73.1 +/- 9.8%, 30 min; 45.0 +/- 16.8%, 60 min. A convenient analysis using a Bond elute SCX cartridge showed slightly larger ratios than those measured by liquid chromatography.
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No-carrier-added (nca) L-["C-methyl]methionine was prepared via the very fast S-alkylation of L-homocysteine adsorbed on AI203/KF with ["C]iodomethane at room temperature in ethanol. The alkylation was realized with a radiochemical yield of 94 \_+ 4% EOB (n = 20). More than 90% (n = 20) of the precu
## Abstract A fast, clean and reproducible method for the manufacture of the radiotracer L‐[methyl‐^11^C]methionine is reported. The reaction at room temperature of the non‐radioactive precursor L‐homocysteine (1 mg solution in ethanol/water 50/50) with [^11^C]CH~3~I in an HPLC loop led to the form