Rapid diagnostics of urinary iodine using a portable EDXRF spectrometer.

A method for urinary iodine diagnostics using a portable energy-dispersion X-ray fluorescent (EDXRF) spectrometer is proposed. The principle of the method consists in excitation of the sample atoms fluorescence by the energy spectrum intentionally formed from the spectrum of an X-ray tube using an optimized X-ray scheme. The optimization by the criterion of the minimum detection limit for L-series iodine fluorescence lines included the calculation of optimal atomic numbers for materials of a re-radiator and a filter, and their thicknesses, the collimation system parameters, and an X-ray tube voltage. Experimentally achieved detection limits were 45 and 75 µg/L by I-Lα and I-Lß lines, respectively, at the theoretically extreme value 30 µg/L. This sensitivity is found to be sufficient for urinary iodine diagnostics in the range from 50 to 200 µg/L. The results obtained from different patients have shown the satisfactory convergence for the iodine concentration determination by Lα and I-Lß fluorescence lines. The simple sample preparation procedure and comparably small sizes of the apparatus allows rapid researches directly in clinical settings.

Determination of coal ash content by the combined x-ray fluorescence and scattering spectrum.

An alternative method is proposed for the determination of the inorganic constituent mass fraction (ash) in solid fuel by the ratio of Compton and Rayleigh X-ray scattering peaks IC/IR subject to the iron fluorescence intensity. An original X-ray optical scheme with a Ti/Mo (or Sc/Cu) double-layer secondary radiator allows registration of the combined fluorescence-and-scattering spectrum at the specified scattering angle. An algorithm for linear calibration of the Compton-to-Rayleigh IC/IR ratio is proposed which uses standard samples with two certified characteristics: mass fractions of ash (Ad) and iron oxide (WFe2O3 ). Ash mass fractions have been determined for coals of different deposits in the wide range of Ad from 9.4% to 52.7% mass and WFe2O3 from 0.3% to 4.95% mass. Due to the high penetrability of the probing radiation with energy E > 17 keV, the sample preparation procedure is rather simplified in comparison with the traditional method of Ad determination by the sum of fluorescence intensities of all constituent elements.