Instrumentation for Assessing mTBI Events
Mark A. Mentzer in Mild Traumatic Brain Injury, 2020
Once the deformation is read from the kinetics spectrum, several quantities may be extracted, which can be used to further characterize different candidate materials. These parameters are illustrated in Figure 3.7. The principle used is the Beer–Lambert law, which is normally used to determine the concentration dependence C of a solute in a solvent from absorbance data A: A = εlC, where l is path length and ε is the extinction coefficient or molar absorptivity. In our case all material parameters may be assumed fixed, with the path length l being replaced by mass m due to delamination. Thus, the transmittance T is proportional to the variation ion path length or, equivalently, the mass change. Therefore a priori measurement of T(t) versus known m can be used to compute the change of mass: T(t) = εmρ where ρ is the density and t is the observation time.
Modelling and analysis of skin pigmentation
Ahmad Fadzil Mohamad Hani, Dileep Kumar in Optical Imaging for Biomedical and Clinical Applications, 2017
The molar absorptivity is a measure of the amount of light absorbed per unit concentration. Molar absorptivity has units of L/mol cm. The absorption of a substance is expressed as an absorption coefficient, μa, which is the molar absorptivity of the chromophores, ε, multiplied by the concentration of the chromophores, c.
Spectroscopy and Fluorimetry
Joseph Chamberlain in The Analysis of Drugs in Biological Fluids, 2018
The molar absorptivity of the solute in spectrophotometry is determined by the chemical structure. A functional group on a molecule which is responsible for absorption is termed a chromophore. Table 4.2 lists the absorption characteristics of a number of functional groups found in drugs.
Improvement of solubility, dissolution and stability profile of artemether solid dispersions and self emulsified solid dispersions by solvent evaporation method
Published in Pharmaceutical Development and Technology, 2018
Muhammad Tayyab Ansari, Muhammad Sohail Arshad, Altaf Hussain, Zeeshan Ahmad
Assay development for artemether, using HPLC (Perkin Elmer, Waltham, MA), required reverse phase C18 columns (4.6 mm × 250 mm, 5 μ) and UV detector recording absorbance at 215 nm wavelength. The mobile phase comprised a mixture of acetonitrile and water (75:25 v/v) at a flow rate of 1 ml min−1. The injection volume was maintained at 20 μl20,21. A calibration curve was established by plotting the area of absorbance peak (recorded from the injection of known quantities of artemether) as a function of concentration (over a range 78–625 μg ml−1) and the data were modeled using a linear regression equation (y = mx + b). A correlation coefficient of 0.9996 indicated that the data are explained using this model. The linear part of the calibration curve infers the samples follow Beer Lambert Law, suggesting that the absorbance (A) of a sample depends on absorptivity coefficient (a), path length (b) and concentration of the analyte (c); A = a(λ) · b · c22. Providing parameters a and b are constant, the absorbance of a sample will be directly proportional to the concentration of drug. This phenomenon is expressed by the linear regression model. This relationship (concentration dependent linear increase for absorbance) is used reliably to determine unknown concentration of drug in samples. The HPLC method was validated according to the guidelines published by ICH. The results of validation parameters are described Table 2.
Synthesis and pharmacological evaluation of novel isoquinoline N-sulphonylhydrazones designed as ROCK inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Ramon Guerra de Oliveira, Fabiana Sélos Guerra, Cláudia dos Santos Mermelstein, Patrícia Dias Fernandes, Isadora Tairinne de Sena Bastos, Fanny Nascimento Costa, Regina Cely Rodrigues Barroso, Fabio Furlan Ferreira, Carlos Alberto Manssour Fraga
The solubility assay was performed considering the absorptivity of compounds under ultraviolet spectroscopy as described by Schneider et al.20 Assay wavelength was determined through λmax characteristic of each compound. Saturated aqueous solutions were prepared (0.8–1.0 mg/mL) and kept under stirring for 4 h at 37 °C. The supernatant was filtered in 0.45 mm filters and transferred to a quartz cuvette (10 mm) for spectra acquisition. Solubility was determined by linear regression used as Excel graph plots, solutions were prepared by dilutions of the original solution in methanol. Data were collected in triplicate and the mean values were used to create the graph plots. The correlation coefficient (R2) values were between 0.9982 and 1.
Evaluation of analytical similarity between trastuzumab biosimilar CT-P6 and reference product using statistical analyses
Published in mAbs, 2018
Jihun Lee, Hyun Ah Kang, Jin Soo Bae, Kyu Dae Kim, Kyoung Hoon Lee, Ki Jung Lim, Min Joo Choo, Shin Jae Chang
Molar absorptivity was determined according to Beer-Lambert Law. First, measurements of OD280 and OD320 were performed using a Beckman DU730 spectrophotometer. Then, protein concentration was obtained from the amino acid analysis using the concentration of ‘robust’ amino acids (where % deviation between observed and expected results was ≤ 5%) such as aspartic acid, glycine, arginine, alanine, proline, valine and leucine. Molar extinction coefficient was calculated with UV absorbance at 280 nm, concentration of protein and molecular weight of CT-P6 and Herceptin®.
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