Our research has focused on developing TOF-SIMS in order to measure organic 15N isotopes in environmental samples [1]. Our goal was to develop a peak-fitting algorithm that would successfully remove the isobaric interferences Al- and 13C14N- from 12C15N- ions under conditions of low mass resolution inherent in environmental samples. We tested a variety of peak fitting models and found that the EMG+GMG model performed better than the standard peak shape shifting method under conditions of high mass resolution unless Al was present as an interference. Under conditions of Al interference and low 15N content, the shape shifting method performed better than the analytical model. As 15N content increased, the analytical model worked comparably or better than the standard method. However, neither method worked satisfactorily when organic 15N standards were analyzed on kaolin clay. Nevertheless, these data emphasize the potential utility of using analytical models to resolve isobaric interferences in TOF-SIMS.
Revised: August 30, 2004 |
Published: June 15, 2004
Citation
Cliff J.B., D.J. Gaspar, P.J. Bottomley, and D.D. Myrold. 2004."Peak Fitting to Resolve CN- isotope Ratios in Biological and Environmental Samples Using TOF-SIMS." In SIMS XIV, proceedings of the fourteenth international conference on secondary ion mass spectrometry and related topics, San Diego, CA, edited by Alfred Benninghoven, 912-916. Amsterdam:Elsevier Science BV.PNNL-SA-39184.