Systematic comparison of post-column isotope dilution using LC-CO-IRMS with qNMR for amino acid purity determination

Determination of urea kinetics by isotope dilution with [13C]urea and gas chromatography-isotope ratio mass spectrometry (GC-IRMS) analysis.

1. Stable urea isotopes can be used to study urea kinetics in humans. The use of stable urea isotopes for studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material. We devised a urea dilution for measurement of the distribution volume, production rate and clearance of urea in healthy subjects and renal failure patients using the inexpensi...

Comparison of the isotope dilution method for determination of the ileal endogenous amino acid losses with labelled diet and labelled pigs.

The aims of the present study were first to compare the amino acid dilution method performed using labelled animals with that using labelled diets, and second to determine real digestibilities and total ileal endogenous losses of N and amino acids. Two diets containing pea cultivars (Solara and Amino) and a protein-free diet were compared in a 3 x 3 Latin-square experiment. The three pigs were ...

Comparison of two isotope dilution/mass spectrometric methods for determination of total serum cholesterol.

Isotope dilution/mass spectrometric methods for total serum cholesterol, developed separately at the Karolinska Institutet (KI) and the National Bureau of Standards (NBS), were compared by applying them to a common set of serum pools. A search for the cause of a systematic difference of a few percent in results from the two methods revealed that the KI cholesterol standard contained lathosterol...

robust control of a high-purity disttilation column using synthesis

Measurement of exogenous gamma-hydroxybutyric acid (GHB) in urine using isotope ratio mass spectrometry (IRMS)

Aim: The objective of the study was to check if gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is a suitable method to differentiate between endogenous and exogenous GHB in urine. Methods: In the presented study, a controlled and monitored administration of 2.25 g GHB (Xyrem) to one participant was carried out. Spot urine samples were collected once before administrat...