Method for isotopic analysis of water in bodily fluids

摘要

Biological fluid samples containing proteins (e.g., blood plasma or saliva) are prepared for isotopic analysis by precipitating the proteins while leaving the isotopic ratio unaffected. This precipitation can involve adding metal ions, salts, organic solvents, or organic polymers. The sample is then centrifuged to allow transfer of the supernatant for isotopic analysis, e.g. by tunable diode laser absorption spectrometry to obtain a quantitative measure of the 2H and 18O isotope levels in the water relative to reference standards.

主权项

1. A method of performing isotopic analysis of water from biological fluid samples, comprising:
obtaining a biological fluid sample, wherein the sample contains water and proteins; preparing the sample prior to analysis by precipitating the proteins in the sample, wherein a protein-precipitating agent added to the sample leaves isotope ratios unaffected for all isotopes that have been selected to be analyzed, and centrifuging the sample sufficient to separate precipitated protein from supernatant liquid; without using any distillation of the sample or of the supernatant liquid prior to quantitative isotopic analysis, transferring, once the centrifuging has stopped, an amount of supernatant liquid from the centrifuged sample to a vial; and conducting a quantitative isotopic analysis of at least one of δ18O, δ17O and δ2H in the undistilled supernatant liquid using laser absorption spectroscopy of water.