Hi Anthony, > Messer Germany did not yet reply me Since Messer was bought by Air Liquide it is sometimes a litte bit pesky to find someone who knows details about the specialty gases. You may try to contact one of the following persons: Wolfgang Zwanzig Air Liquide Deutschland GmbH Verkauf Spezialgase Berliner Allee 51 D-30855 Langenhagen Tel.: +49 511 + 78 615-31 Fax: +49 511 + 78 615-10 [log in to unmask] or: Air Liquide Deutschland GmbH Entwicklung Spezialgase Labor Batavastrasse 47 47809 Krefeld Frau Antje Pfeuffer [log in to unmask] [in case mail is not working try to replace "messer" by "airliquide"] greetings, Robert -- Dr. Robert van Geldern Leibniz Institute for Applied Geosciences (GGA) S3: Geochronology and Isotopehydrology Stilleweg 2, 30655 Hannover, Germany phone: +49-(0)511-643-2313 (office), -2539 (lab) fax: +49-(0)511-643-3665 mailto:[log in to unmask]