Have you ever wondered which analysis to choose as the best means of obtaining XRF results? Understanding the fundamentals is important as accuracy, turnaround time and cost are all influenced by the correct selection of a suitable analysis.

Quantitative Analysis

For calibration procedures that use matrix correction, the type of correction depends upon the degree to which the matrix correction terms differ between samples and standards. Influence coefficient equations correct for the net effect of both enhancement and absorption and it is usually only necessary to correct for interfering effects from the major elements. Most manufacturer supplied software packages include equations such as: the Lachance-Traill, Lucas-Tooth, Pyne and the COLA equations. Influence coefficient equations are applicable to major, minor and trace elements. These equations do not however, correct for errors in sample preparation, chemical effects, surface effects, particle size or mineralogical effects. Typically calibrations are forced through the origin in a constrained regression so that outliers do not skew the calibration line and yield erroneous results.

ACT-UIS offers quantitative analysis of major and minor elements in various samples including coal ashes, beach sands, iron ore and exploration samples using the fused bead preparation method. The instruments are calibrated using a wide spectrum of certified reference materials and matrix effects are corrected using the relevant influence coefficients.

For process control projects the pressed powder pellet technique can also be utilized depending on sample matrix. In this case, matrix matched standards must be used to reduce mineralogical effects as far as possible. 

Qualitative Analysis

Can also be termed “semi-quantitative” analysis and can be performed using Standardless Fundamental Parameters (SLFP) where no standards or calibration curves are used. With SLFP, an algorithm computes both the intensity to concentration relationship and the absorption effects. Results are typically within 10-20% of actual values.

At ACT-UIS the XRF spectrometers are able to automatically process a wide scan of elements using state-of-art software. The software package is fully calibrated and installed at the instrument manufacturer’s factory and can produce results within 3 minutes. Other features of the software are: automatic smoothing, background subtraction, overlap and matrix corrections, calculation of “semi-quantitative” concentrations and normalization. All these benefits aid to yield a fast and easy means of “semi-quantitative” analysis for an unknown sample.

By providing both types of analysis the XRF Section at ACT-UIS endeavors to ensure that all clients’ needs and requirements are met in terms of cost efficiency, data accuracy and sample turnaround times.