Isogeochemists: I was having problems last night with Isogeochem recognizing my e-mail address, which I hope are fixed now, so let me send the message about the helium we use at the University at Albany that I wanted to send last night, for Bill and others interested: We use Air Products "Ultra-Pure Carrier Grade" He, which is supposed to be 99.9995% He (excluding Ne), with our Carlo Erba NA 1500 NC Series II EA and Micromass Optima. This grade is between UHP at 99.999% and Research or Chromatographic Grade which are both 99.9999%. Our price (through the University's ChemStores, is about $72 for a 291 cf tank, about $20 more than HP He (99.997%). The N2 and O2 appear to be quite low in comparison with levels in UHP He. We have never felt the need to employ traps or scrubbers. Maybe a good and cost-effective solution. 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 http://www.albany.edu/geosciences/sirmslab.html ---------------------------------------------------------------------------