Spectroscopy is one of the most important analytical tools used for the characterization of samples. Spectroscopic analysis helps explore composites and provides important information, such as their electronic and optical properties, chemical composition, element type, and crystallinity, which is of immense help to researchers. Over the years, scientists have advanced spectroscopic techniques for the accurate and rapid analysis of compounds.
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Spectroscopy and Chemical Analysis
Chemical analysis plays a pivotal role in drug manufacturing, environmental monitoring, medical diagnosis, forensic survey, and food analysis. Analytical chemistry and the advancement of various analytical tools and techniques have largely contributed to the scientific research and discovery of various products that have become an essential part of our lives.
Scientists perform spectroscopic analysis to understand the chemical nature of a compound. More specifically, such analysis helps understand the toxic nature, stability, quality, purity, composition, and many more aspects of the compound under study. It also helps determine qualitative and quantitative aspects of a compound. A wide range of biological, organic, and inorganic samples can be studied via spectroscopic tools.
Research associated with analytical chemistry heavily depends on the developments in earlier instrument construction and methods. The methodological or instrumental advancements are predominantly targeted towards enhancing sensitivity, accuracy, simplicity, and providing more complex information rapidly. These developments also ensure the formulation of sustainable analytical methods. The selection of suitable spectroscopic techniques and instruments is extremely important in scientific research. The most important criteria for such selection are based on the sensitivity and the nature of the samples to be studied.
Spectroscopy: Principles and Importance
Spectroscopy is based on the study of absorption and emission of light and radiation by any matter. Spectroscopy also deals with the interactions between particles, i.e., electrons, protons, and ions, as a function of their collision energy. Analysis of the high energy collisions has helped scientists understand electromagnetic forces and other strong and weak forces between particles. Spectroscopy has played an important role in the development of many fundamental theories of physics, such as theories of relativity, quantum mechanics, and quantum electrodynamics.
As spectroscopic techniques are highly sensitive, they can detect single atoms and also different isotopes of the same atom among 1020 atoms or more of different species. Scientists use spectroscopic techniques to detect minute or trace amounts of contaminants. Some of the spectroscopic techniques that can estimate minuscule frequency shift in narrow spectroscopic bands are microwave, optical and gamma-ray spectroscopy.
Advancements In and Different Types of Spectroscopic Analysis
Advancements in spectroscopy have helped various fields of science and technology. For instance, radio-frequency spectroscopy of nuclei in a magnetic field has helped develop one of the most important medical techniques, which is known as magnetic resonance imaging (MRI). This advanced tool is used to study the internal soft tissue of the body with extraordinary resolution. Optical spectroscopy is used to analyze the chemical composition of matter and to study its physical structure.
Mass spectroscopy (MS) is one of the most popular spectroscopic techniques used by chemists, pharmacologists, biologists, and medical practitioners. MS techniques have advanced dramatically, especially, with regards to quantitative accuracy, and improving the resolution of MS data that include precise molecular structural-derived information. Two of the advanced MS techniques used in proteomics studies are matrix-assisted laser desorption-ionization time-of-flight MS (MALDI-TOF MS) and liquid chromatography-electrospray ionization MS (LC-ESI-MS). These techniques are linked with computers and software which help analyze and identify unknown compounds.
Energy-dispersive X-ray spectroscopy (EDX) is often integrated with scanning tunneling microscopy and transmission electron microscopy to study the elemental composition of materials. X-ray photoelectron spectroscopy (XPS) is a quantitative technique used for analyzing the elemental composition of a material. This analytical tool determines the binding states of the elements present in the sample. XPS is generally used to investigate textile surfaces. Recent advancements in the XPS technique have been Hard X-ray Photoelectron Spectroscopy (HAXPES), which provides information about the chemical, electronic, magnetic, and structural nature of materials.
Fourier transform infrared (FT-IR) is a rapid, informative, and non-destructive technique that provides information about the chemical composition and structural features of a sample. It helps determine the functional groups of a molecule and also assesses the purity of a chemical compound. This analytical technique provides the chemical structure of the biological tissues by generating important chemical peaks.
Raman spectroscopy is typically used for quantitative and qualitative characterization of polymeric samples. This spectroscopic tool provides important information about the physical and chemical properties of a polymer which enables polymer engineers to develop advanced polymers with various applications. Some of the developments in Raman spectroscopy include enhancement in the Raman signal of heterogeneous catalysts. These are used by surface-enhanced Raman spectroscopy (SERS), and shell-isolated nanoparticle surface-enhanced Raman spectroscopy (SHINERS). Raman spectroscopy and FT-IR can characterize the chemical bonds in hybrid composites.
UV-Vis spectroscopy, as well as fluorescence spectroscopies, are used to determine the optical properties of a material. Scientists have reported that owing to advancement in the chemometric tools and instrumental developments, UV-Vis spectroscopy can now authenticate geographical origins, purity, and quality of a varied range of food products such as fish, meat, oil, tea, rice, wine, beer, and juices.
In the last decade, near-infrared (NIR) spectroscopy has become one of the most rapidly advancing spectroscopic techniques that has significantly contributed to the study of physical chemistry. This technique is associated with the analysis of the anharmonic nature of molecular vibrations or unique intermolecular interactions. Additionally, mid-infrared (MIR) is an extremely sensitive, rapid, and specific tool that provides molecular information used in biological analysis.
References and Further Reading
Ozaki, Y. et al. (2021) Advances, challenges and perspectives of quantum chemical approaches in molecular spectroscopy of the condensed phase. Chemical Society Reviews. 50. pp. 10917-10954. DOI https://doi.org/10.1039/D0CS01602K
Hess, C. (2021) New advances in using Raman spectroscopy for the characterization of catalysts and catalytic reactions. Chemical Society Reviews. 5. pp. 2895 – 3630. https://doi.org/10.1039/D0CS01059F
Stoner, J. O. et al. (2021). Spectroscopy. Encyclopedia Britannica. [Online] Available at: https://www.britannica.com/science/spectroscopy
Beć, K. B. and Huck, C. W. (2019) Breakthrough Potential in Near-Infrared Spectroscopy: Spectra Simulation. A Review of Recent Developments. Frontiers in Chemistry. 7, 48. https://doi.org/10.3389/fchem.2019.00048
Bergquist, J. and Turner, C. (2018) Analytical chemistry for a sustainable society – trends and implications. Analytical and Bioanalytical Chemistry. 410. pp. 3235–3237. https://doi.org/10.1007/s00216-018-1036-4