Spectroscopic Techniques
Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf in Fingerprinting Analysis and Quality Control Methods of Herbal Medicines, 2018
Mass Spectrometry is a powerful technique for identifying unknowns, studying molecular structure, and probing the fundamental principles of chemistry. It can provide us with useful structural information for drug discovery and has been recognized as a sensitive, rapid, and high-throughput technology for advancing drug discovery from herbal medicine in the post-genomic era. It is essential to develop an efficient, high-quality, high-throughput screening method integrated with mass spectroscopy (Zhang et al., 2016). Mass spectroscopy is one of the primary spectroscopic methods for molecular analysis available to an organic chemist. It is a microanalytical technique requiring only a few nanomoles of the sample to obtain characteristic information pertaining to the structure and molecular weight of an analyte. It involves the production and separation of ionized molecules and their ionic decomposition products and finally the measurement of the relative abundance of the different ions produced (Yerlekar and Kshirsagar, 2014). It is, thus, a destructive technique in that the sample is consumed during analysis. In most cases, the nascent molecular ion of the analyte produces fragment ions by cleavage of the bond and the resulting fragmentation pattern constitutes the mass spectrum. Thus, the mass spectrum of each compound is unique and can be used as a “chemical fingerprint” to characterize the sample.
Breathomics and its Application for Disease Diagnosis: A Review of Analytical Techniques and Approaches
Raquel Cumeras, Xavier Correig in Volatile organic compound analysis in biomedical diagnosis applications, 2018
As the name suggests, samples for GC-MS must either be in the gaseous phase or, more likely, be transferred into the gaseous phase by heating. The sample is then injected into the chromatograph where an inert carrier gas (usually helium, but increasingly hydrogen) is used to transport it through a packed or open, tubular (capillary) column. The column is typically coiled and very thin (0.25 mm internal diameter) allowing even those tens of meters in length to be housed within a relatively small temperature controlled oven. The exact length of the column depends on the type and speed of the desired analysis, but for metabolomic studies, longer columns (∼30 meters) are generally used as these provide better chromatographic resolution and ensure maximum separation of the analytes in complex samples. Separation of compounds occurs due to differing rates of partitioning of the components of the sample between the internal lining of the column (stationary phase) and the carrier gas (mobile phase). This means each compound exits the column at a different time (known as the retention time). The mass spectrometer (MS) can then be used to detect eluting compounds, traditionally using electron impact (EI) ionization to ionize the compound, and then to measure the mass to charge ratio of each ion and generate a unique mass spectrum for the compound. SPME can also be used to absorb and pre-concentrate volatile compounds in breath prior to analysis.
Low Energy Particle Accelerators and Laboratories
Vlado Valković in Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Recent progress has allowed the spot size to be reduced to the micron level. Reported applications of this technique include the mapping of structures in multilayer semiconductor devices to monitor the manufacturing process, the study of high-Tc superconductor compound structures, the analysis of weld failures, etc. The combination of RBS, which allows the depth profile to be determined, with PIXE can give a three-dimensional picture of the element distribution in the sample. While with ion beam analysis, the accelerator is used to bombard the sample with ions and detect the induced atomic or nuclear processes, in accelerator mass spectrometry (AMS) the constituents of the sample are ionized, accelerated and identified by mass spectrometry. The high sensitivity of AMS finds applications in the semiconductor industry. Semiconductor devices are rapidly degraded by even a small concentration of some impurities which can be readily detected by AMS. Up to now, this was essentially studied by Secondary Ion Mass Spectrometry (SIMS). AMS gives a dramatic improvement of two orders of magnitude in sensitivity. The sample is ionized by a cesium beam.
Human tear fluid analysis for clinical applications: progress and prospects
Published in Expert Review of Molecular Diagnostics, 2021
Sphurti S Adigal, Alisha Rizvi, Nidheesh V. Rayaroth, Reena V John, Ajayakumar Barik, Sulatha Bhandari, Sajan D George, Jijo Lukose, Vasudevan. B. Kartha, Santhosh Chidangil
In view of the research methodologies being employed at present, some pertinent procedures can be considered for further research and development. The three technologies being pursued at present, in increasing complexity, cost of equipment and expertise required, can be put in the order (i) optical spectroscopy (absorption, fluorescence, scattering), (ii) separation methods (HPLC/UPLC/SDS-PAGE) and mass spectroscopy, followed by (iii) hyphenated methods. It is thus appropriate to think how these three technologies can be coordinated. A suitable modus operandi can be: carry out universal screening using the optical spectroscopy technique, since it needs only trained technicians, can be coupled to automatic data processing to give objective conclusions, requires miniature portable/hand-held equipment only, and above all, preserves the same sample for further tests if warranted. Cases diagnosed as abnormal can then be sent for HPLC/UPLC studies, and if desired, or in case the specific marker identities will be useful for therapy planning and decision making, MS-dependent separation techniques can be used. Such a coordinated procedure will be most helpful for universal healthcare, especially, under low-resource settings.
Recent advances in screening and diagnosis of hemoglobinopathy
Published in Expert Review of Hematology, 2020
Kanjaksha Ghosh, Kinjalka Ghosh, Reepa Agrawal, Anita H. Nadkarni
Far more precise molecular biological techniques are often needed but may prove very expensive. However, data from both parents can be extremely useful at this point in time. Moreover, the newborn screen often involves screening for multiple diseases from blood spots collected on Guthrie card [34,35]. This bloodspot presents some technical challenge for use in HPLC system. Because the dried blood spot causes a partial degradation of hemoglobin over time and haptoglobin present in the plasma of blood spot combines with different hemoglobins at a different rate and the combined proteins produce additional elution peaks in HPLC system. Several companies have newborn screening reagents to be used in HPLC machines modified for the purpose for screening sickle cell disease (Biorad). In future, mass spectroscopy with its various modifications can be used for this purpose. High-throughput molecular protocols are now developing for different conditions and are also available for hemoglobinopathy detection [36].
Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review
Published in International Journal of Radiation Biology, 2020
Michalina Gramatyka, Maria Sokół
Two main methods that can be employed for metabolomics are NMR (Nuclear Magnetic Resonance) spectroscopy and MS (Mass Spectrometry). NMR employs the magnetic properties of the atomic nuclei placed in a strong magnetic field, whereas MS is based on the ion formation and their separation according to their mass-to-charge (m/z) ratio (Barba and Garcia-Dorado 2012). NMR spectroscopy is a less sensitive method than mass spectrometry, but it allows the measurement of metabolites in liquids, cellular extracts, tissues and even living organisms without the need for complicated sample preparation. It enables identification of metabolites difficult to ionize or with an identical m/z ratio, it also allows to determine the chemical structures of unknown molecules and to study the molecular interactions and dynamics (Rhee and Gerszten 2012; Markley et al. 2017). Mass spectrometry is a more sensitive method than NMR and allows the identification of hundreds of metabolites. However, it requires a more complex sample preparation and leads to its destruction, thus cannot be used in in vivo studies (Alawieh et al. 2013). The advantages of both methods, NMR spectroscopy and mass spectrometry, can be exploited by combining both techniques. Such an approach provides better results by improving the identification and quantitation of compounds in mixtures (Markley et al. 2017; Bingol 2018).
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