Optimization of Ag isotope-ratio precision with a 128-channel array detector coupled to a mattauch-herzog mass spectrograph

Isotope-ratio measurements are necessary in a wide range of applications. The precision of these measurements is of utmost importance because it governs the ability to distinguish differences between samples. Often, simultaneous isotope detection is necessary to reach the precision values needed for an analysis to be conclusive. Furthermore, the more isotope ratios that can be precisely determined at once, the better the chances of distinguishing between samples. Therefore, detector arrays, able to simultaneously monitor a broad range of isotopes, are attractive. Such an array detector, termed the focal plane camera (FPC), has been shown to be capable of achieving impressive precision values (0.02% RSD) within relatively short integration times (200 s). However, because the channels of the FPC array detector are inherently discrete, optimization of peak integration methods is important. This paper compares isotope-ratio precision values based on different peak integration methods of raw and zero-filled interpolated data. Also, problems associated with peak drift are explored and the use of flat-topped peak shapes for improved isotope-ratio precision levels are investigated.