Determination of oxygen triple isotope ratios of silicates without cryogenic separation of NF 3 – technique with application to analyses of technical O 2 gas and meteorite classification

A novel technique is described to determine Δ′ 17 O TFL with high accuracy and precision by using infrared (IR) laser fluorination with F 2 as the reaction gas. The technique includes precise monitoring of the intensity ratio of the 14 NF   2 +( m/z 52) to O 2 signals. The correlation between the intensity of 14 NF   2 +and positive error in δ 17 O VSMOW allows correction of measured data to obtain reliable Δ′ 17 O TFL values. The resultant error in Δ′ 17 O TFL of a single measurement after correction is in the range of ±0.06‰, i.e. sufficiently small to permit the technique to be useful for meteorite classification. Our data for technical O 2 , in combination with literature data, suggest a negative anomaly of tropospheric air O 2 with Δ′ 17 O TFL  = –0.344 ± 0.015‰ (1σ). Copyright © 2007 John Wiley & Sons, Ltd.