Dear Drew and others, It appears we are all in the same boat, and some companies are trying to get European CO for us (MG Industries), but this taking some time. We are also taking delivery of a TC/EA soon, and I have asked several times to the isotope community if anyone has any ideas about how to approach this problem. Bill Showers is also a good person to contact. Do not order any US-CO. We did and made the $850-mistake, with a high purity tank and a delta of about -350 per mil. You are better off using your own internal standards than a ref. gas with such a negative value. -Bill -- William Anderson Assistant Professor Earth Sciences Department and Southeast Environmental Research Center Florida International University Mailing address: Dept. of Earth Sciences, PC 344 FIU 11200 S.W. 8th Street Miami, FL 33199 USA office: 305 348 2693, sec. 348 3572 SERC stable isotope lab: 305 348 3044 fax: 305 348 3877 email: [log in to unmask]