Quality assurance in the determination of peak areas from complex spectra obtained by instrumental neutron activation analysis of geological material

Instrumental neutron activation analysis (INAA) of geological material invariably results in complex spectra containing multiple overlapping peaks, especially if rare earth elements are present in the sample. Since quantitative INAA is dependent on precise determination of peak areas the choice of an appropriate algorithm for analysis is an important factor. A simple peak boundary algorithm is compared to a Gaussian peak fitting algorithm for the analysis of various trace elements in new Japanese rock standards. The following rocks were analyzed by INAA: three andosites (JA-1, JA-2, JA-3); three basalts (JB-1a, JB-2, JB-3); two granodiorites (JG-1a, JG-3); one granite (JG-2); one gabbro (JGb-1); two rhyolite (JR-1, JR-2); two feldspars (JF-1, JF-2) and one periodate (JP-1). It will be shown that while an optimized peak boundary method of analysis is adequate for single well resolved peaks, a Gaussian peak fitting method is better suited to the analysis of overlapping peaks