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Flow injection with chemical reaction interface-isotope ratio mass spectrometry: an alternative to off-line combustion for detecting low levels of enriched 13C in mass balance studies.


J Am Soc Mass Spectrom. 1999 Feb;10(2):153-8. Unique Identifier :

We have evaluated the potential of flow injection chemical reaction interface isotope-ratio mass spectrometry to replace radioactive labeling techniques in material balance studies. A sample is flow injected and transmitted through a desolvation system followed by combustion to form 13CO2 with a microwave-powered chemical reaction interface. We can detect trace amounts of a 13C-labeled drug (3'-azido-3'-deoxythymidine, AZT) in urine or feces. Our ability to quantify less than 100 ng/mL of excess 13C (approximately 1 microgram/mL of 13C-labeled AZT) from a sample equivalent to 10 microL of urine is superior to previous detection limits for 13C in urine that use off-line combustion methods. Parallel studies using 14C-labeled AZT showed that our stable isotope method provides comparable percent excretion data for urine and feces. These results support previous findings that mass balance studies could be carried out with isotope-ratio mass spectrometer, here using doses as low as 1-2 mg/kg.

JOURNAL ARTICLE Algorithms Animal Anti-HIV Agents/ANALYSIS/PHARMACOKINETICS Carbon Dioxide/ANALYSIS Carbon Isotopes/ANALYSIS Male Rats Rats, Sprague-Dawley Spectrum Analysis, Mass/*METHODS Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Zidovudine/ANALYSIS/PHARMACOKINETICS


Information in this article was accurate in May 30, 1999. The state of the art may have changed since the publication date. This material is designed to support, not replace, the relationship that exists between you and your doctor. Always discuss treatment options with a doctor who specializes in treating HIV.