SOME INVESTIGATIONS ON STABILITY AND PRECISION OF AN HR-ICP-MS

Over a period of 4 months long-and short time stability (precision) of a high resolution inductively coupled plasma mass spectrometer (HR-IC P-MS) was investigated using an ELEMENT (Finnigan MAT, Germany) instru ment. By using a special torch design, significant improvements could be achieved. Without changing any electrical parameters of the mass sp ectrometer, the long time stability over a time period of 4 months was measured as about +/- 15% for In-115 for all three steps of resolutio n (300, 3000, 7500). The short time stability over a period of 2-8 h w as measured as about +/- 10% (at maximum), also nearly independent of the resolution. The main result was the near independence of the stabi lity from the mass-spectrometer itself, but a strong dependence on the sample introduction system, the ICP-torch and the cones.