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1 X‐Ray Fluorescence and Comparison with Other Analytical Methods (AAS, ICP‐AES, LA‐ICP‐MS, IC, LIBS, SEM‐EDS, and XRD)

       Kanishka Rawat1, Neha Sharma2, and Vivek Kumar Singh3

       1 Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India

       2 School of Physics, SMVD University, Katra, 182320, Jammu and Kashmir, India

       3 Department of Physics, University of Lucknow, Lucknow, 226007, Uttar Pradesh

1.1 Introduction

      Most highly complex structured materials require good analytical techniques that can furnish information about the spatially distributed elements in the materials and permit the examination of their structures. Many analytical methods exist which provide insight into the chemical compositions and structure of the materials. Each technique has its own advantages and limitations in terms of analytical performance, sensitivity, accuracy, and applicability. X‐ray fluorescence (XRF) is an elemental analysis technique that is used for elemental and chemical analysis of various materials including glass, metals, and ceramics. XRF is also seeing increased application and greater utility in the analysis of biological materials [1–3]. In XRF analysis, X‐ray photons characteristic of the elemental makeup of the sample material are emitted as it is bombarded with highly energetic X‐ray beams [1–3]. In most circumstances, XRF is considered non‐destructive. The other factors responsible for its wide adoption are low cost of sample preparation, relative ease, and stability.

      Several elemental analysis techniques such as laser induced breakdown spectroscopy (LIBS), inductively coupled plasma mass spectroscopy (ICP‐MS), ion chromatography (IC), etc. are widely used for the analysis of materials, particularly biological samples such as tooth, bone, nail, stone, blood, cancerous tissues, etc. [4–7]. There are many other similar methods such as time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) and proton‐induced X‐ray emission spectroscopy (PIXE) that have many important biomedical applications. Inductively coupled plasma (ICP) is also one of them, which is a plasma source wherein energy is supplied by electric currents generated by electromagnetic induction [3]. ICP has numerous applications such as in nuclear technologies, isotopic speciation, and detection of chemical elements. IC separates polar molecules and ions on the basis of their chemical affinity with regards to the ion exchanger [3]. It can be operated on all charged molecules, like bio‐molecules (especially amino acids), large proteins, small nucleotides etc. It has many clinical and industrial applications. In this chapter, we present briefly the position of XRF including micro‐XRF (μ‐XRF) among some other the analytical methods including ICP‐AES/MS, IC, LIBS, TOF‐SIMS, and PIXE.

1.2 Analytical Capabilities of XRF and Micro‐XRF

      XRF spectrometry is generally used in two different kinds of configurations: wavelength dispersive mode (WD‐XRF) and energy dispersive mode (EDXRF) [8, 9]. Both of them have different ways of detecting and analyzing emitted fluorescent X‐ray photons. ED‐XRF spectrometers have detection systems which examine the distinct energies of the X‐ray photons coming directly from the sample material. The XRF spectrum is generated by detecting and plotting the relative count numberings of X‐rays at each energy value. The energy dispersive detectors basically involve the creation of electron–hole pairs in semiconductor materials (Si). After the emergence of silicon drift detectors (SDD), EDXRF is

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