The calibration of an automatic X‐ray spectrometer using calculated relative intensities

Abstract

It is demonstrated that an evaluation procedure for conversion of X-ray intensity to element concentration used on an existing spectrometer can be used in reverse to provide intensity data for calibrating another spectrometer. Extensive remeasurement of standards is thereby eliminated. Intensities are calculated for postulated changes in composition and these form the input data for the spectrometer computer regression program. Such data are free from measurement error. Calibration and a coefficients from calculated intensities are found to give analytical results of an accuracy comparable with those derived from experimentally produced calibrations. The intensity calculations can be extended to include the determination of calibration and a coefficients without using the spectrometer regression programs. Considerable expense and effort can be saved. ~ ~ ~~ ~-INTENSITY CALCULATIONS The calibration equation used by the PW1450 spectrometer takes the form CT = (D t ER) [ 1 t (aij Cj/ 1 OO)]where C = concentration; D = calibration intercept (in concentration units); E = calibration slope factor; R = spectrometer intensity function; i = analyte; j = interfering element; aij = a coefficient, i.e. the constant representing the effect of element j on element i.The PW1450 spectrometer possesses facilities for correcting raw intensities for spectral background intensity and CCC~049-8246/78/0007-0190 $02.50

X-ray spectrometry

“…The transfer possibilities for «-factors from one instrument to another are used by Chamberlain (103) to invert from concentrations to intensities and hence provide calibration data for a second spectrometer. Plesch (104,105) attempts to show a theoretical basis for the Rasberry and Heinrich equation for matrix correction, while Riveros et al ( 106) extend it to include higher order effects.…”