Dirk Wissmann explains how the latest innovations can deliver WD-XRF performance at an ED price
Energy dispersive X-ray fluorescence analysis (ED-XRF) is still sometimes seen as a technique that only permits a qualitative statement or that is able to quantitatively determine the contents of just a few elements. But this is definitely a thing of the past.
For example, new developments of the Spectro Xepos ED-XRF spectrometer, such as ‘adaptive excitation’, lead to improved sensitivity and detection limits and yield remarkable gains in precision and accuracy. The heart of this excitation system is the newly developed X-ray tube in combination with polarised and bandpass-filter excitation. The higher sensitivity available with this excitation is utilised together with a sophisticated high-resolution detector and a new readout system. Together they contribute to the analyser’s high sensitivity and low background, for greater precision and lower LODs.
With regard to operation, the customer specifies an analysis task prioritised for either high sample throughput or best precision. The analyser is then configured to produce optimum excitation conditions for a specified group or groups of elements. The X-ray beam is optimised by fixed excitation optics with different beam channels. So each excitation configuration can precisely fit the user’s chosen analytical task.
Unlike most ED-XRF elemental analysers, the X-ray tubes in Spectro Xepos spectrometers remain powered on between measurements to prevent on/off variations from affecting readings. This ensures long-term stability, realises a high degree of precision in elemental analysis – up to three times better than before – and delivers substantially improved analytical accuracy for concentrations from trace elements to major components.
For operators who require speed more than utmost precision, these analysers can significantly cut measurement times, while maintaining precision levels comparable to traditional ED-XRF spectrometers. The system’s high speed helps to achieve analyses of most samples within a few minutes.
Innovations such as these make modern ED-XRF instruments predestined for critical tasks from rapid screening elemental analysis for environmental and waste sampling to demanding applications in research, academia and geological science. Combined with the typical XRF advantages, such as simplicity, minimal sample preparation, non-destructive testing, etc., ED-XRF is now recognised by experts as being a proven and successful analytical method that is excellently suited to a wide range of applications such as chemical and petrochemical production, and the manufacture of cement, cosmetics, food, pharmaceuticals, and more.
Thus, for many applications, advanced ED-XRF analysers such as the Spectro Xepos deliver a performance that is comparable to wavelength dispersive X-ray fluorescence (WD-XRF) analysers, while exhibiting a considerably lower cost of ownership.
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Dirk Wissmann is with Spectro Analytical Instruments.
