X-Ray Fluorescence Spectrometry – Determination of Composition Using XRF by LSM Analytical Services

Background

LSM Analytical Services offer a large and diverse range of modern analytical testing facilities that cater for a vast range of industry sectors. LSM’s success has been achieved by building on a strong reputation for low cost, fast accurate turnaround. The laboratory activities are backed up by accreditation to the ISO 17025 (UKAS) and 9001:2000 laboratory and quality management standards. LSM is able to offer complete analytical solutions from its internationally recognised team of technical experts, with in depth knowledge, allowing its customers to benefit from impartial guidance.

LSM’s range of analytical services includes:

• X-Ray Fluorescence Spectrometry (XRF)
• X-Ray Diffraction (XRD)
• ICP Optical Emission Spectrometry (ICP-OES)
• Atomic Absorption Spectrometry (AAS)
• Carbon, Sulphur, Nitrogen, Oxygen Analysers
• Boron analysis by the Neutron Transmission method
• Colorimetric and Volumetric Analysis
• Particle Size Analysis

X-Ray Fluorescence Analysis

LSM Analytical Services large range of analytical techniques includes instrumentation for XRD analysis; one of two of the most widely applied analytical techniques based on X-rays:

• XRF (X-Ray Fluorescence) for the elemental or oxide content of a material
• XRD (X-Ray powder Diffraction) for identification of crystalline compounds or phases

X-Ray Fluorescent (XRF) Spectrometers use a spectroscopic technique, which is commonly used for solids, in which x-rays are used to excite a sample and generate secondary x-rays.

Types of X-Ray Fluorescence Spectrometers

XRF provides determination of major and trace elements in solids. There are 2 types of XRF spectrometers:

• Wavelength dispersive (WDX or WDS); superior resolution and detection limits
• Energy dispersive (EDX or EDS); smaller, often portable

Sample Preparation – The Borate Glass Bead Technique

As with any analytical method, sample preparation is crucial and LSM was one of the early pioneers of the Borate glass bead technique, developing methodology for analysis of refractory and rare earth oxide mixtures as well as a range of Ferroalloys, Steels and hard metal Carbide powders. This is a valuable way to eliminate errors with materials, which exhibit varying composition, or are difficult to present in other forms.

How X-Ray Fluorescence Determines Chemical Composition

The x-rays used for X-Ray Fluorescence (XRF) have as wide a range of wavelengths as possible (i.e. they are as near as possible to white light). The beam of x-rays enters the atoms of the sample and for each different element one wavelength (“colour”) of x-rays is given out, the characteristic radiation.

The detector is moved to the position at which the characteristic radiation for each element being analysed leaves the sample and registers the strength of the beam. The intensity (strength) of the characteristic x-rays given out measures the amount of that element in the sample. In reality elements are measured simultaneously using a number of pre-assembled fixed channels placed around the sample. Each is effectively a self-contained spectrometer, with a crystal and detector tuned to receive a specific wavelength.

Semi-Quantitative Analysis Using XRF form LSM Analytical

LSM also provides an excellent semi-quantitative package, which covers all the elements from Fluorine to Uranium measurable by XRF in one analysis. Useful results can be obtained from even small samples. By combining a semi-quantitative analysis with XRD, a cost effective investigative tool is available for deposits, corrosion, contamination or other unknowns.

Source: LSM Analytical Services

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