Table 2 demonstrates the excellent standard deviationachievable (0.4 wt.-% for 60 s measuring time) for measurement of P-concentration. It should be noted that a high totalspectral intensity of more than 50,000 cps is the result of veryhigh flux excitation by an instrument using a polycapillary X-rayoptic emitted from a relatively small measuring spot of lessthan 50 µm Ø.In the case of standard aperture beam collimation, the totalmeasuring time for similar precision is expected to be a factorof 2-3 X longer.