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Optical Spectroscopy for the Detection of Necrotizing Enterocolitis
Published in David J. Hackam, Necrotizing Enterocolitis, 2021
Optical spectroscopy is a technology that has shown potential promise in this regard and merits more widespread understanding and investigation. Spectroscopy is a measurement of the interaction of electromagnetic radiation, or light, with tissue. The electromagnetic spectrum is the range of wavelengths and respective frequencies that light waves can manifest, spanning the following commonly known energies from lowest to highest: radio, microwave, infrared, visible (400–700 nm wavelength), ultraviolet, x-ray, and gamma (Figure 20.1). Whenever photons (the basic building blocks of electromagnetic radiation that have properties of both a particle and a wave) encounter an object, various fractions of the light are simultaneously reflected, absorbed, and scattered (Figure 20.2). The proportion of each of these fractions varies by wavelength and is determined by the characteristics of the target and its tendency to interact with each respective wavelength. A spectrophotometer is a device that quantifies this interaction by detecting the fraction of light that is either transmitted (i.e., not absorbed) or reflected. Spectrophotometers are widely used in a diverse array of scientific fields to characterize objects of interest, including physics, astronomy, materials science, chemistry, and biochemistry.
Current Perspectives and Methods for the Characterization of Natural Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Muthusamy Ramesh, Arunachalam Muthuraman, Nallapilai Paramakrishnan, Balasubramanyam I. Vishwanathan
UV spectroscopy is another type of spectroscopy. The basic principles of UV spectroscopy are absorption of light and make the changes of the incident after passing to samples. It lies between the wavelength of 200–400 nm and visible spectroscopy lie at the wavelength of 400–800 nm. The instrument used for obtaining the spectrum is UV-Vis spectrophotometer. Ethyl alcohol and hexane are the solvents widely used to prepare the sample for UV-Vis spectroscopy. UV-Vis spectrum assists to characterize the aromatic group of compounds and conjugated dienes in qualitative analysis. In quantitative analysis, UV-Vis spectroscopy also helps to determine the molar concentration of constituents present in a given sample. In addition, it is also used to detect impurities, isomers, and molecular weight (Perkampus, 2013). UV-Vis spectroscopy was employed to characterize diarylheptanoids in association with other spectral techniques (Alberti et al., 2018). Diarylheptanoids have a specific absorption range, i.e., 250–290 nm. Acetonitrile was used as a solvent to get the UV-Vis spectrum. Further, a wider absorption band observed for curcumin, i.e., 410–430 nm. Keto-enol tautomerism of curcumin was characterized from the intra- and intermolecular hydrogen bonding. UV-Vis spectroscopy method is also used for the quantification of the curcuminoid content of Curcuma Longa extract (Alberti et al., 2018). The UV-Visible spectroscopy-based characterized phytoconstituents and marine compounds are listed in Table 2.2.
Reactivities of Amino Acids and Proteins with Iodine
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
It is seen that Edelhoch’s procedure, in contrast to the other methods discussed so far, is essentially a single-wavelength approach, in which the second parameter to be measured is generated by a change in ionization. Similar, single-wavelength techniques have also been described by Brown et al.181 and Demeester et al.182 It is thought that the accuracy of spectrophotometric determinations is improved by keeping instrument settings unchanged. Demeester and colleagues also appraised some of the techniques already mentioned and found the Goodwin-Morton method167 satisfactory; the Bencze-Schmid approach180 gave good results as long as tryptophan and tyrosine were present in approximately equimolar ratios, while the Brown method181 was less accurate at any ratio of both amino acids. The Beaven-Holiday technique111 suffers from the defect that the wavelength and extinction coefficients are based on the free amino acids, and take no direct account of the red shifts which accompany peptide formation.164
Comparison of tiotropium delivery with the ODAPT adapter and a valved holding chamber
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2021
Rym Mehri, Abubakar Alatrash, Nicholas Ogrodnik, Kenny Lee Slew, Edgar A. Matida
The experimental setup was then disassembled and washed separately to quantify the amount of medication deposited within each component. All the different components were washed using distilled water to dissolve the medication. The ACI deposition plates were placed into separate Petri dishes with 15 mL of distilled water and were shaken for 1 minute each. The face, facemask, and ODAPT adapter (for test case 3 and 4) were carefully cleaned with 10 mL, 10 mL and 8 mL of distilled water, respectively. The induction port (IP) only (for test case 1 and 2) or the IP and the tubing coupler (for the test case 3, 4, 5 and 6) were washed with 15 mL of distilled water. For test case 5 and 6, the VHC was washed using 25 mL of distilled water. Each component was left in their respective solution for 2 hours to allow for a consistent dissolution of the medication. Spectrophotometry was used to obtain the concentration of each solution at 237 nm (8453 UV-Visible Spectrophotometer, Agilent Technologies, Santa Clara, CA). Further details on the spectrophotometry methodology are provided in Mehri et al.15 Three repeats of each test were performed.
Development of UV–visible spectrophotometric methods for the quantitative and in silico studies for cilazapril optimized by response surface methodology
Published in Drug Development and Industrial Pharmacy, 2021
Notably, previous researches have revealed the diverse independent methods for CLZ determination. There are many reports documented on high performance liquid chromatography [14], liquid chromatography–mass spectrometry [15], RP-LC [16], square wave voltammetry, stripping voltammetry, spectrofluorimetry [17], spectrophotometry [18–23], and capillary zone electrophoresis. However, the methods on LC–MS, RP-LC, square wave voltammetry, and stripping voltammetry are difficult to incorporate. The advantages achieved in this study over the reported spectrophotometric methods in the literature are in terms of good linearity, detection, and quantification limits. Actually, the donor–acceptor based assays are not recent and have been studied and applied for spectrophotometric and sometimes fluorimetric assays of hundreds of pharmaceutical compounds. In drug analysis, the wide applicability of these color reactions is available in the literature [24–36]. Therefore, the spectrophotometry, coupled with donor–acceptor complex phenomenon, is explored in the present study.
Pyrrole derivatives as potential anti-cancer therapeutics: synthesis, mechanisms of action, safety
Published in Journal of Drug Targeting, 2020
Halyna Kuznietsova, Natalia Dziubenko, Iryna Byelinska, Vasyl Hurmach, Andriy Bychko, Oksana Lynchak, Demyd Milokhov, Olga Khilya, Volodymyr Rybalchenko
To investigate the precise mechanisms of interaction of PDs with the lipid matrix of the cell membrane we used the method of infra-red (IR) spectroscopy of PC dry films modified by tested compounds. The lipid samples were taken from a system composed with two non-mixing solutions (aqueous 10−5M PD solution and n-decane 0.5% PC solution) in 20 min after their contact. The sample was applied on calcium fluoride substrate and then dried up with warm air (+55 °C). The thickness of dry films used in experiment was 10.2 ± 0.3 μm. IR transmission spectra were recorded using a two-beam IR spectrophotometer. Each spectrum was truncated to the range of 4200–1200 cm−1. A background spectrum was collected by placing a clean CaF2 substrate in the sample holder. The background was checked at the beginning of the experiment and then after every fourth sample. Identification of absorption bands was conducted according to [40]. All assays were performed in triplicate.