Oliver, I've had very good luck using an approach similar to your capillary method to introduce volatile trihalomethanes into a sealed quartz tube to combust them to CO2. Seems this should work for your application too. I used KIMAX-51 capillary tubes made by Kimble (1.5-1.8 mm diameter by 90 mm length). Flame-seal one end of a capillary tube, then heat and stretch the glass near that end to get a very thin, fragile section that is still open to the rest of the capillary. Practice a bit to find the right balance between too thin (breaks during handling or closes completely) and not-thin-enough (takes a lot of effort to break when in your quartz tube). It's a very fine line. Fill the capillary with your acid, then flame-seal the open end carefully. Insert the capillary tube in the quartz tube and seal. Some moderate shaking can snap the capillary at its weak section and release the acid. Good luck. Cheers, Bryan -------------------------------------------------- Dr. Bryan E. Bemis U.S. Geological Survey 345 Middlefield Road, MS 434 Menlo Park, CA 94025 (650) 329-5603 Office (650) 329-5590 Fax [log in to unmask] |---------+---------------------------> | | Oliver Zafiriou | | | <[log in to unmask] | | EDU> | | | Sent by: Stable | | | Isotope | | | Geochemistry | | | <ISOGEOCHEM@LIST| | | .UVM.EDU> | | | | | | | | | 08/13/02 12:23 | | | PM | | | Please respond | | | to Stable | | | Isotope | | | Geochemistry | | | | |---------+---------------------------> >---------------------------------------------------------------------------------------------------------------| | | | To: [log in to unmask] | | cc: | | Subject: [ISOGEOCHEM] How to releasing reagents into pre-sealed tubes? | >---------------------------------------------------------------------------------------------------------------| We want to streamline a 13C/12C procedure by releasing strong acid into seawater samples while keeping them sealed in quartz tubes. ARe there tested methods for such an operation? We're thinking of adding a small glass capillary in which conc. sulfuric is sandwiched between two small air spaces, with the ends sealed with pre-autoclaved, molten paraffin wax (or other meltable, inert, CO2-free sealant), then heating /shaking to release. Maybe the bugs have been worked out of some such schemes? Thanks in advance for your experiences/advice. OLIVER C. ZAFIRIOU MS4, Fye Building Department of Marine Chemistry & Geochemistry Woods Hole Oceanographic Institution Woods Hole, MA 02543-1543 USA email: [log in to unmask] Tel: (508) 289-2342 Fax: (508) 457-2164