Isotopic disproportionation during hydrogen isotopic analysis of nitrogen-bearing organic compounds.

Rationale: High-precision hydrogen isotope ratio analysis of nitrogen-bearing organic materials using high-temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H(2)) has been suspected as a possible cause of incomplete H(2) yield and hydrogen isotopic fractionation.

Methods: The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400 °C, have been compared using a selection of nitrogen-bearing organic compounds, including caffeine.