Stable isotope analysis of biochars

For routine determination of stable isotope ratios of light elements (C, N, O, H, S) in organic samples, solids must be converted to gases for introduction into an isotope ratio mass spectrometer (IRMS).1The conversion to gases is achieved by preparation systems such as those described in Chapter 4, where samples are combusted or pyro-lysed and the gases thus liberated are separated from each other by gas chromatography (GC).2The gases are introduced to the IRMS through a fused-silica capillary with an inner diameter of 0.05–0.1μm which allows the preparation system to operate at atmospheric pressure, while the IRMS maintains the high vacuum needed to analyse the gases of interest