For calibration of a LCA4 IRGA analyzer featuring a window including the absorbance range of 13CO2, I need a mixture of 15ppm 13CO2 and 1000ppm 12CO2 in Nitrogen. I need the gas mixture in a Pressure cylinder of aproximately 20 bar. thank you, Dr. Wolfgang Wanek Department of Chemical Physiology of Plants Institute of Plant Physiology University of Vienna Althanstrasse 14 A-1091 Vienna, Austria Tel: + 431 31336 1432 Fax: + 431 31336 776 Email: [log in to unmask]