APPLICATION OF A DUAL-MODE DETECTION SYSTEM FOR ICP-MS .1. DETERMINATION OF MAJORS, MINORS, AND TRACES IN GEOSTANDARDS

The high-gain pulse-counting detection systems currently used in ICP-MS, although exhibiting excellent characteristics for trace analysis, have only a finite gain. At count rates of the order of 106 cps, gain suppression occurs, thus effectively limiting the upper measurable concentration ranges to a few μg mL-1. It is possible to utilize such detections in an analogue mode, whereby the output signal is a direct function of the applied voltage. In this paper, the applicability of a detection system employing both analogue and pulse-counting detection is evaluated, with particular emphasis on the determination of majors, minors, and traces in geological reference materials. In addition, two sample preparation modes are compared; in the first, a conventional lithium metaborate fusion is utilized, while alternatively, a rapid slurry technique is found to be particularly effective for some more volatile elements.