Dear isogeochemists, Do some of you have knowledge or references concerning the measurement of 13CO2/12CO2 ratios (either at 13C-enriched or natural abundances) by infrared absorbance techniques (FTIR, laser diodes, NDIR ?) What are the performances of such methods ? Thanks in advance from France. ------------------------------------------------------ Jerome Balesdent, Directeur de Recherches INRA Laboratoire d'Ecologie Microbienne de la Rhizosphere (UMR CNRS/CEA #163) DEVM - CEA - Centre de Cadarache F13108 Saint-Paul-lez-Durance Cedex tel : +33 4 42 25 77 54 secr: +33 4 42 25 27 53 fax : +33 4 42 25 66 48 [log in to unmask] ------------------------------------------------------