Measurement of blood volume with an enriched stable isotope of chromium (53Cr) and isotope dilution by combined gas chromatography-mass spectrometry.

Determination of selenium in biological materials by stable isotope dilution gas chromatography-mass spectrometry.

Determination of Key Intermediates in Cholesterol and Bile Acid Biosynthesis by Stable Isotope Dilution Mass Spectrometry

For more than a decade, we have developed stable isotope dilution mass spectrometry methods to quantify key intermediates in cholesterol and bile acid biosynthesis, mevalonate and oxysterols, respectively. The methods are more sensitive and reproducible than conventional radioisotope (RI), gas-chromatography (GC) or high-performance liquid chromatography (HPLC) methods, so that they are applica...

Testosterone measurement by isotope-dilution liquid chromatography-tandem mass spectrometry: validation of a method for routine clinical practice.

BACKGROUND Immunoassay is unsatisfactory for measuring the testosterone concentrations typically found in women. Bench-top tandem mass spectrometers are a viable alternative technology for measurements in the clinical laboratory. METHODS We used stable-isotope dilution liquid chromatography-tandem mass spectrometry (ID/LC-MS/MS) to measure testosterone in plasma and serum. The sample volume w...

Precise measurement of chromium isotopes by MC-ICPMS.

We report novel analytical procedures allowing for the concurrent determination of the stable and mass-independent Cr isotopic composition of silicate materials by multiple collector inductively coupled mass spectrometry (MC-ICPMS). In particular, we focus on improved precision of the measurement of the neutron-rich isotope 54Cr. Because nitride and oxide interferences are a major obstacle to p...

The scope of mass spectrometry in clinical chemistry.

Several aspects of mass spectrometry and gas chromatography-mass spectrometry are reviewed, including ionization methods, repetitive scanning, selected ion monitoring, and stable isotope measurement. I discuss the application of these and other mass spectrometry methods to the investigation of compound classes relevant to clinical chemistry, to the assessment of inborn errors of metabolism, and...