Hi Jose! I use a tube cracker that is a combination of the Coleman (1981) and Caldwell et al. (1983) designs (see references previously mentioned by Andrea Lini). I buy glass ball-and-socket joints from Kontes and have them make some minor modifications (although any glassblower could do it too). I have the end of 18/7 ball joint sealed, and a 3-mm-thick, 10-mm-diameter fritted glass disk inserted in the 18/9 socket joint. The tube cracker accepts 6-mm O.D. glass tubes that are about 170 mm long. The ball-and-socket joint is greased with Apiezon L and secured with a pinch clamp. The open end of the socket joint is attached to the mass spectrometer inlet with an Ultra-torr Cajon connector rather than an Ace Thread connector. E-mail me directly if you are still interested in dimensions and Kontes part numbers. Steve --------------------------------------------------------------------------- Stephen S. Howe Office: (518) 442-5053 Dept. of Earth & Atmos. Sciences Stable Isotope Lab: (518) 442-4471 Earth Science 352B FAX: (518) 442-5825 University at Albany E-mail: [log in to unmask] 1400 Washington Avenue http://www.albany.edu/geosciences/sshowe.html Albany, NY 12222-0001 ---------------------------------------------------------------------------