Study on the Determination of Heavy Water in Plasma or Urine

[摘要] A technic has been described for determining the excess of deuterium oxide in plasma or urine, by directly measuring 19:18 ratios in vapor from these fluids with a mass spectrometer of suitable design. Although the 19:18 ratio for water varied with sample size and other experimental conditions, the increment in ratio per unit concentration of added D2O remained quite uniform. A virtually linear relationship between the increment in ratio and the concentration of added D2O also facilitated checking the calibration. The time required for flushing out deuterium when a Pyrex inlet system was used could be minimized by carrying out both the calibrations and the analyses in triplicate, without intermediate flushing, but with adherence to a strict time schedule. Results calculated from increments in ratio for the second and third samples of vapor rarely differed from their average value by more than ± 0.8 per cent.

[学科分类] 过敏症与临床免疫学