EXPERIMENTAL INVESTIGATION OF HETEROGENEITY EFFECTS IN X-RAY-FLUORESCENCE ANALYSIS OF HAIR

The effect of heterogeneity on the accuracy of analytical results was experimentally investigated for some biologically important elements i n hair, viz. S, Cl, K and Ca. Measurements were carried out by energy- dispersive x-ray fluorescence spectrometry using annular Fe-55 radiois otope source excitation. The differences between the concentration val ues from direct hair analysis, using bunches of hair strands for the m easurements, and those from ground and pelletized hair samples were co mpared. On average, the discrepancy in the measured concentrations was ca. 5% for Ca, whereas for S, Cl and K it was higher at ca. 10-15%. G ood agreement was found between the experimental values and the theore tical predictions of other workers.