H/ H measurements of amphiboles and nominally anhydrous minerals (clinopyroxene, garnet and diamond) using high-temperature continuous flow elemental analyser/pyrolysis/isotope ratio mass spectrometry.

Rationale: We have used a high-precision, high-efficiency method for the measurement of the H/ H ratios of hydrous silicates (amphiboles) and nominally anhydrous minerals (NAM) such as clinopyroxene, garnet and diamond, which are usually extremely resistant to pyrolysis. This opens up new fields of investigation to better understand the conditions of formation for deep-Earth minerals.

Methods: The technique described here involves Isotope Ratio Mass Spectrometry (IRMS) on-line in continuous flow mode with an Elemental Analyser (EA) using "purge and trap" technology rather than separation by conventional packed column gas chromatography (GC).

18O/16O ratio measurements of inorganic and organic materials by elemental analysis-pyrolysis-isotope ratio mass spectrometry continuous-flow techniques.

We have used a high-precision, easy, low-cost and rapid method of oxygen isotope analysis applied to various O-bearing matrices, organic and inorganic (sulfates, nitrates and phosphates), whose (18)O/(16)O ratios had already been measured. It was first successfully applied to (18)O analyses of natural and synthetic phosphate samples. The technique uses high-temperature elemental analysis-pyrolysis (EA-pyrolysis) interfaced in continuous-flow mode to an isotope ratio mass spectrometry (IRMS) system.

Essential methodological improvements in the oxygen isotope ratio analysis of N-containing organic compounds.

The quantitative conversion of organically bound oxygen into CO, a prerequisite for the (18)O/(16)O analysis of organic compounds, is generally performed by high-temperature conversion in the presence of carbon at ∼1450°C. Since this high-temperature procedure demands complicated and expensive equipment, a lower temperature method that could be utilized on standard elemental analyzers was evaluated. By substituting glassy carbon with carbon black, the conversion temperature could be reduced to 1170°C.