Total reflection energy-dispersive x-ray fluorescence spectrometry using monochromatic synchrotron radiation. Application to selenium in blood serum

Abstract

Monochromatic synchrotron X-radiation at The National Synchrotron Light Source (NSLS) has been Investigated as an excitation source for the direct energy-dispersion X-ray fluorescence (EDXRF) spectrometrlc analysis of metals In solution at parts per billion (ppb) levels In the total reflection geometry. A minimum detection limit (mdl) of 8 ppb was determined for selenium In human blood serum and In ; reposed NBS-SRM 1598 bovine serum. The results show that this method Is sufficiently sensitive for analysis of Se In blood serum. Se Is present at about 30-100 ppb In human bl od serum and about 40 ppb In NBS-SRM 1598. The lov «st concentration of selenium measured was 9.7 ± 0.5 ppi In NBS-SRM 1843b trace elements In water where a mdl of 3.6 ppb Se was obtained. Minimum detection limits were also calculated to compare relative sensitivities of tube-excited secondary target conventional sources when illuminating a large sample area with NSLS excitation when probing a much smaller sample area.

Synchrotron radiation-induced total reflection X-ray fluorescence analysis

“…The first SR experiments were published in 1986 by Iida et al [14] followed by results of several other authors [15][16][17]. A recent review on SR-TXRF analysis was given by Streli et al [18].…”

Effect of synchrotron polarization on grazing incidence X-ray fluorescence analysis

“…Maximal signal to noise ratio can be realized if the uorescence signal is measured in a position, where the contribution of anisotropic scattered radiation is minimal. [5][6][7][8][9][10] In the literature, several attempts have been made earlier that report signicant reduction of the spectral background and hence improved detection sensitivities of the XRF technique. Embong et al 11 have reported sub-ppm level detection sensitivities using a three-dimensional polarization excitation geometry for multi-element sediment samples by means of variation of various experimental parameters like excitation geometry, X-ray energy, secondary targets, operating voltage and current of the X-ray tube source, and thickness of lters installed in the spectrometer.…”