Take a look at the archives about this problem and use of quartz inserts or inconel metal inserts. As recent as a few months ago. Jason Jason Curtis, Ph.D. Stable Isotope Mass Spec Lab manager Senior Associate-In Geochemistry Department of Geological Sciences University of Florida Gainesville, FL 32611 +1-352-275-8642 On Apr 12, 2017, at 9:36 AM, wissel2b <[log in to unmask]<mailto:[log in to unmask]>> wrote: Hello Sofia, GFF and GFC filters melt at 1000 C. We analyze POM on filters at 820 C instead without any problems. I'll send you a paper later today. Cheers, Bjoern On Apr 12, 2017, at 5:08 AM, Sofia Goncalves <[log in to unmask]<mailto:[log in to unmask]>> wrote: Dear Isogeochem members, We are analysing some difficult samples of POMs for d15N and d13C on our EA 2000 IRMS Delta V Advantage. These samples are colleted and analyzed on filters and have a high C/N. Some of these samples gives peaks with strange shape and integration. The separation is not good either. The analytical conditions are as follows: - carrier flow 90ml/min - oxygen flow: 200ml/min - reference flow: 200ml/min - ox. reactor: 1020 Celsius - red. reactor: 650 C - oven: 45 C Could anyone help me improve this type of analysis? Thank you very much. Best regards, Sofia