The chemical determination of zirconium in polymctallic silica matrices is difficult and lengthy, hccause of the necessary prior separations of interfering ele-men&i.
The analysis of sands is cvcn more troublesome because the chemical composition of sands varies greatly and consiclerablc amounts of iron and titanium arc present as well as admixtures of calcium and rare-earth clcmcnts. The method presented below permits zirconium to be determined in the prcscnce of varying amounts of iron and titanium. ASALYSIS 01: %II~COI;IUXl-REAHISG SASIIS
13ccause of the presence of several metals in the test materials, a nondispcrsive X-ray fluorescence method was chosen. The characteristic S-ray K-series of zirconium was excited by a io%d source emitting the characteristic KAg series of 22.6 keV. Such radiation, the energy of which is slightly above the absorption edge of zirconium (x8.0 kcV) gave a good excitation yield. The activity of the source amounted to ca. 30 or xoo PC depending on the particular procedure.
A simple standard apparatus was used, consisting of a H.V.-supply. a kryptonfilled proportional counter with a resolution of about 18% at 6.4 keV, a pulse amplifier and scaler. A multichannel analyser was used in some measurements, but is not needed for routine work. The measurements were made in the normal compact geometry, i.e., the source was placed on the counter window with the sample above this windowz.
-rhe time of a single measurement was 1 min.
In the spectrum of sand samples, apart from peaks corresponding to the Kseries of zirconium (15.7 keV), iron (6.4 keV) and the peak of scattered radiation (about 20.7 kcV), several escape peaks are also present. Since the counting rate of pulses from zirconium for the applied source activity was sufficiently high, pulses in the range of escape peaks were eliminated by a suitable choice of discrimination level. This also allowed the characteristic radiation of iron and titanium to be cut off, so that the only radiation registered was due to the K-series of zirconium and the Compton-scattered primary radiation. The separation of these two radiation peaks was quite good, though not complete (Fig. ).
Asal.