J. Rudolph et al., A NOVEL METHOD FOR COMPOUND-SPECIFIC DETERMINATION OF DELTA-C-13 IN VOLATILE ORGANIC-COMPOUNDS AT PPT LEVELS IN AMBIENT AIR, Geophysical research letters, 24(6), 1997, pp. 659-662
A novel method for the compound specific determination of delta(13)C i
n VOC is presented. It combines a cryogenic preconcentration procedure
with gas chromatograph,ic separation, on-line combustion and isotope
ratio mass spectrometry. The method allows the determination of delta(
13)C values of VOC at sub ppb levels with a precision of 0.5 parts per
thousand. The procedure is suitable for routine operation. The accura
cy of the method is of the same quality as the reproducibility of the
measurements. The first ever measurements of delta(13)C in selected VO
C in clean air are presented and compared with data from samples of co
ntaminated air. The variability in the delta(13)C values of atmospheri
c VOC is much larger than the accuracy and precision of the measuring
method. Hence the technique will be a very valuable tool to complement
concentration measurements of VOC and to improve our understanding of
the processes governing the distribution of VOC in the atmosphere.