Grazing-exit XRF

Some important characteristics of XRF techniques for element analysis are list in Table 3.1. 

As mentioned above, EDXRF is a non-destructive multielemental analytical technique. Because the beam size of the primary X-ray can be monitored with a slit or focusing system, XRF is capable of microscopic analysis, supplying information about the 2D distribution of trace elements. The technique can, thus, be used for imaging of trace elements in a biological specimen, also for direct elemental determination in protein bands after slab-gel electrophoresis. Reviews concerning analysis of metalloproteins with XRF after electrophoresis separation have been published.  

Method Detection limit Matrix effect Detectable elements Spectral interference Preferred sample type Lateral resolution Multi- element 

GEXRF ED ngmL WD Medium Z 11 Z 4 High Low Liquid (residue) Good Yes Limit 

TXRF ngmL Low Z 11 High Liquid (residue) Poor Yes 

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An obvious drawback of grazing incidence is poor lateral resolution because the incident X-rays irradiate the whole sample surface at small angles. An inverse arrangement, known as grazing-exit XRF, enables surface analysis of small regions to be carried out. 

Grazing-exit XRF (GE-XRF) is a method related to TXRF, where the primary X-ray irradiates a sample perpendicularly to the reflector surface carrying the sample, while the X-ray fluorescence is collected under a grazing angle at small take-off angles. The experimental setup is shown in Figure 3.9. 

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