Dear Isogeochemers, Absolutely trouble-free storage of water samples (and of other liqids as well) can be easily achieved in simple glass ampules that are commercially available from lab suppliers. Hand-held portable butane mini-torches are cheap and can be refilled. Their heat is sufficient to seal the low-melting glass of the ampules, even in the field. I recommend to pre-heat the new ampules in an oven to 450 deg C overnight to burn away organic dust, then to keep the ampules in a clean zip-lock bag. The glass can be easily engraved to permanently identify samples. Once you have your samples under glass, there is no worry ever about isotope fractionatioin during storage. ******************** Arndt Schimmelmann Biogeochemical Laboratories Indiana University Department of Geological Sciences 1005 East Tenth Street Bloomington, IN 47405-1403 U.S.A. ph 812-855-7645 fax 812-855-7961 ********************