Abstract
A simple and versatile loop-solid phase extraction (SPE) method was developed for the automated preparation of [11C]doxepin, a histamine H1 receptor antagonist, from [11C]methyl triflate ([11C]MeOTf). This labeling agent was passed through a Teflon or Tefzel loop coated internally with a film of the precursor solution. The reaction products were then flushed from the loop to a short SPE column, where they were concentrated and then injected onto a semi-preparative HPLC column simply by switching an injection valve. By applying this combined loop-SPE technique the whole procedure turned out to be easily automated. The formation of [11C]methylated doxepin ([11C]methyldoxepin) was observed and the ratio of doxepin to methyldoxepin was found to be clearly correlated with the mass ratio of nordoxepin to MeOTf. This observation highlights the importance of [11C]MeOTf specific activity in the [11C]methylation of secondary amines. Using this method, [11C]Doxepin was prepared in over 40% radiochemical yield from high specific activity [11C]MeOTf.
Original language | English |
---|---|
Pages (from-to) | 271-280 |
Number of pages | 10 |
Journal | Journal of Labelled Compounds and Radiopharmaceuticals |
Volume | 45 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2002 May 30 |
Keywords
- Automated preparation
- Carbon-11
- Doxepin
- Loop-SPE method
- Methyl triflate
ASJC Scopus subject areas
- Analytical Chemistry
- Biochemistry
- Radiology Nuclear Medicine and imaging
- Drug Discovery
- Spectroscopy
- Organic Chemistry