Detection of 13C labelled compounds by gas chromatography coupled to atomic emission detection — Application to caffeine metabolites

Some unique properties of gas chromatography coupled with atomic-emission detection

“…For isotope studies it is frequently more advantageous to use the emission of a molecular species of the element investigated rather than the atomic emission itself, because the wavelength separation can be larger and less overlap of the emission signals is observed. Thus 12 C and 13 C can be detected well separated on the second order lines at 342.57 and 341.71 nm, respectively, where the carbon monoxides emit [94]. Nitrogen isotopes were found to perform better as the CN species than at the atomic emission line [95].…”

“…Studies with 13 C have included chlorinated dibenzodioxin [52], 13 C-labeled amino acids from whisky brewing [97], 13 C-labeled progesterone [98], and urinary metabolites from labeled caffeine [94,99]. A compound-independent response was observed for both 13 C and 15 N so quantification required one standard only.…”

Synthesis and purification of 13C labelled xanthine derivatives

“…[13CH3]3) is one of the isotopomers used in the study of caffeine metabolism (1)(2)(3)(4)(5)(6)(7). It is metabolised by the liver under the influence of the microsomal oxidizing system using different * to whom correspondence should be sent.…”

“…The physicochemical behaviour of 3-isobutylparaxanthine-7-[ 13CH3] is, in many respects, similar to that of methylxanthines (MX) so this compound can constitute an ideal internal standard for their quantitative determination after derivatization (2,4).…”

Drug Monitoring in Human Plasma by Capillary Gas Chromatography Coupled with Atomic Emission Detection. Potential and Limitations

“…GC-AED has been utilized for the determination of triclosan in human dental plaque [7], to study 13 C labeled metabolites of caffeine in human urine [8,9], for quantitative determination of propofol in rat liver microsomes [10], and for the quality control of selenium containing amino acids in pharmaceutical formulations [11]. However, attempts to determine drug substances in human plasma by GC-AED have not been published, except from a brief study on Imuthiol R [12].…”