T.B. Coplen Willi A. Brand 2001 <p><span>An interlaboratory comparison of forty isotope-ratio mass spectrometers of different ages from several vendors has been performed to test&nbsp;</span>²<span>H/</span>¹<span>H performance with hydrogen gases of three different isotopic compositions. The isotope-ratio results (unsufficiently corrected for H</span>₃<span>&nbsp;</span>⁺<span>&nbsp;contribution to the m/z = 3 collector, uncorrected for valve leakage in the change-over valves, etc.) expressed relative to one of these three gases covered a wide range of values: –630‰ to –790‰ for the second gas and –368‰ to –462‰ for the third gas. After normalizing the isotopic abundances of these test gases (linearly adjusting the δ values so that the gases with the lowest and highest&nbsp;</span>²<span>H content were identical for all laboratories), the standard deviation of the 40 measurements of the intermediate gas was a remarkably low 0.85‰. It is concluded that the use of scaling factors is mandatory for providing accurate internationally comparable isotope-abundance values. Linear scaling for the isotope-ratio scales of gaseous hydrogen mass spectrometers is completely adequate.</span></p> application/pdf 10.1007/s002160100814 en Springer Link An interlaboratory study to test instrument performance of hydrogen dual-inlet isotope-ratio mass spectrometers article