Dachun, You can use it but if you plan to run it as a dry salt you need to give the nitrate some cation other than H+ to avoid the volatility of HNO3. We did this by adding silver oxide, but for d15N only you could probably use other oxides or possibly a base. -- Steve Steven Silva U.S. Geological Survey 345 Middlefield Rd., Mailstop 434 Menlo Park, CA 94025 ph: (650) 329-4558 fax: (650) 329-5590 email: [log in to unmask] Dachun Zhang <[log in to unmask] To: [log in to unmask] COM> cc: Sent by: Stable Subject: d15N of nitrate Isotope Geochemistry <[log in to unmask] UVM.EDU> 04/12/2005 04:23 PM Please respond to Stable Isotope Geochemistry Dear All: Can the solution passed through the AG 50W-X8 resin be used for d15N of nitrate? Cheers. Dachun Zhang Zymax Isotope Lab