X-Ray Fluorescence in Biological Sciences

Principles, Instrumentation, and Applications

Vivek K. Singh, Jun Kawai, Durgesh K. Tripathi, Vivek K. Singh , Jun Kawai , Durgesh K. Tripathi

• Editore: Wiley
• Anno: 2022
• ISBN:
  9781119645580
• Edizione: 1
• Argomento: Physical Sciences
• Categoria: Spectroscopy & Spectrum Analysis

X-Ray Fluorescence in Biological Sciences

Discover a comprehensive exploration of X-ray fluorescence in chemical biology and the clinical and plant sciences

In X-Ray Fluorescence in Biological Sciences: Principles, Instrumentation, and Applications, a team of accomplished researchers delivers extensive coverage of the application of X-ray fluorescence (XRF) in the biological sciences, including chemical biology, clinical science, and plant science. The book also explores recent advances in XRF imaging techniques in these fields.

The authors focus on understanding and investigating the intercellular structures and metals in plant cells, with advanced discussions of recently developed micro-analytical methods, like energy dispersive X-ray fluorescence spectrometry (EDXRF), total reflection X-ray fluorescence spectrometry (TXRF), micro-proton induced X-ray emission (micro-PIXE), electron probe X-ray microanalysis (EPXMA), synchrotron-based X-ray fluorescence microscopy (SXRF, SRIXE, or micro-XRF) and secondary ion mass spectrometry (SIMS).

With thorough descriptions of protocols and practical approaches, the book also includes:

• A thorough introduction to the historical background and fundamentals of X-ray fluorescence, as well as recent developments in X-ray fluorescence analysis
• Comprehensive explorations of the general properties, production, and detection of X-rays and the preparation of samples for X-ray fluorescence analysis
• Practical discussions of the quantification of prepared samples observed under X-ray fluorescence and the relation between precision and beam size and sample amount
• In-depth examinations of wavelength-dispersive X-ray fluorescence and living materials

Perfect for students and researchers studying the natural and chemical sciences, medical biology, plant physiology, agriculture, and botany, X-Ray Fluorescence in Biological Sciences: Principles, Instrumentation, and Applications will also earn a place in the libraries of researchers at biotechnology companies.

Part I
General Introduction

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 mainly used. As compared with EDXRF, WDXRF is quite expensive and is not needed for testing materials for steel industry or ceramics industry, for which EDXRF is enough. In recent years, EDXRF leads over WDXRF and is a powerful tool for elemental analysis to determine major, minor, and trace elements in biological samples [3]. EDXRF spectrometers are simpler in design, smaller, and more cost effective than other technologies. Examples of some common EDXRF applications include: quantifying atomic elements in: food, animal feed, cosmetics, woods, toothpaste, cement, kaolin clay, granular catalysts, ores, and many others.

One more difference between the techniques is that with an EDXRF system, the full spectrum is obtained virtually at once. So, a range of elements belonging to the periodic table can be determined simultaneously. With an WDXRF system, the spectrum has been procured by a series of discrete step, which is time‐consuming, and also expensive due to the restricted number of detectors.

1.2.1 Micro‐XRF

XRF is a bulk technique with the analysis range varying from several millimeters to several centimeters. Inhomogeneous samples compacted into a pellet form and thereby make it little time consuming. Also it requires a large amount of sample material for the analysis. Many advancements have been made in the field of X‐ray optics that gave rise to originate to narrow X‐ray beams (1 mm to 10 μm). Such developments allow even a solo microscopic particle to be discretely analyzed for an explicit elemental image of high spatial resolution.

XRF [7] is based on an energy‐dispersive detection system. For the generation of precise and accurate elemental images consisting of thousands of pixels, a fast ...