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Drug Substance and Excipient Characterization
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Parind M. Desai, Lai Wah Chan, Paul Wan Sia Heng
In addition to its application in the separation and identification of materials, chromatography is also employed to detect potential interactions between materials. Both thin-layer chromatography and liquid chromatography are commonly employed for this purpose. In thin-layer chromatography, the stationary phase consists of a powder adhered onto a glass, plastic, or metal plate. The powders commonly used are silica, alumina, polyamides, celluloses, and ion-exchange resins. Solutions of the drug, excipient, and drug–excipient mixture are prepared and spotted on the same baseline at one end of the plate. The plate is then placed upright in a closed chamber containing the solvent, which constitutes the mobile phase. As the solvent moves up the plate, it carries with it the materials. Those materials that have a stronger affinity for the stationary phase will move at a slower rate. The material is identified by its Rf value, which is defined as the ratio of the distance traveled by the material to the distance traveled by the solvent front. The position of the material on the plate is indicated by spraying the plate with certain reagents or exposing the plate to ultraviolet radiation. If there is no interaction between the drug and excipient, the mixture will produce two spots whose Rf values are identical to those of the individual drug and excipient. If there is interaction, the complex formed will produce a spot whose Rf value is different from those of the individual components.
Quality Control of Ayurvedic Medicines
Published in D. Suresh Kumar, Ayurveda in the New Millennium, 2020
V. Remya, Maggie Jo Alex, Alex Thomas
H.P.T.L.C. is an advanced version of T.L.C. The modern H.P.T.L.C. technique, combined with an automated sample application and densitometric scanning, is sensitive, completely reliable and suitable for qualitative and quantitative analysis. H.P.T.L.C. is a valuable tool for reliable identification, as it can generate chromatographic fingerprints that can be visualized and stored as electronic images. The advantages of H.P.T.L.C. include high sample throughput and low cost per analysis. Multiple samples and standards can be separated simultaneously and sample preparation is easier, as the stationary phase is disposable. In H.P.T.L.C. all steps of the T.L.C. process are computer-controlled (Srivastava 2011; Wagner et al. 2011).
Peptide Separation by Reverse-Phase High-Performance Liquid Chromatography
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
Improvement in chromatographic efficiency is achieved by decreasing the particle size of the stationary phase. The resulting decrease in sample bandspreading allows better resolution, faster separation, and higher detection sensitivity. The basis of the technique commonly known as HPLC is a stationary phase made of 10-μm diameter or smaller particles to yield High Performance. High Pressure is then required to make the liquid mobile phase flow through a column of this packing, and the necessary pump, sample injection valve, detector, and associated equipment lead to a High-Priced system. Snyder and Kirkland12 provide a thorough discussion of the theory and practice of HPLC.
Ameliorative effects of hexane extract of Garcinia kola seeds Heckel (Clusiaceae) in cisplatin-induced hepatorenal toxicity in mice
Published in Drug and Chemical Toxicology, 2022
Adeniyi Folayan, Emmanuel Akani, Olayinka A. Adebayo, Olubukola O. Akanni, Solomon E. Owumi, Abiola S. Tijani, Oluwatosin A. Adaramoye
The Agilent technologies 7890 GC system model instrument was used for the analysis. The model of the detector was Agilent technologies 5975 MSD (Mass Spectrometer Detector). The mobile phase was the carrier gas (Helium, 99.99% purity), while the stationary phase was the column. The model of the column was HP5 MS with length 30 m and internal diameter 0.320 mm, while the thickness was 0.25 µm. The oven temperature program was the initial temperature of 80 °C to hold for 1 minute. It increases by 10° C per minute to the final temperature of 240° C to stay for 6 minutes. The injection volume was 1 µL, and the heater or detector temperature was 250°C. The sample (HEGK) was put in a vial, which was later placed in an auto-injector sample compartment. The automatic injector injects the sample into the liner. The mobile phase pushes the sample from the liner into the column, where separation takes place into different components at different retention times. The MS then interpret the spectrum MZ (mass to charge ratio) with molar mass and structures.
On the potential of micro-flow LC-MS/MS in proteomics
Published in Expert Review of Proteomics, 2022
Yangyang Bian, Chunli Gao, Bernhard Kuster
The stationary phase, i.e. the chromatographic column, is central to any LC separation. The physical dimensions of the column and material packed into the column determine the type of analyte and the quantities that can be separated (particle material, internal diameter (i.d.)) and the efficiency of the separation (length, particle size, flow rate, temperature etc.). As for other areas of chromatography, the trend toward smaller particle sizes and the concomitant necessity to separate at very high pressure (ultra-high performance liquid chromatography, UHPLC, >1,000 bar) has also been followed in proteomics [8–10]. The use of very small-diameter columns has dominated the field for many years because this offered the sensitivity required to support proteomic applications. As discussed below, this ethos is now beginning to change. For the purpose of the discussion in this review, LC columns are broadly classified into four groups that are based on the internal diameter (Figure 1). Analytical columns typically have 2.1–4.6 mm i.d. and are used at flow rates of >200 μL/min. Columns with 0.5–1 mm i.d. and a flow rate of 10–200 μL/min are referred to as micro-flow, and columns with 150–300 μm i.d. and a flow rate of 1–10 μL/min are known as capillary flow. Finally, columns with an i.d. <100 μm and used at a flow rate <1 μL/min are termed nano-flow [11,12].
Unraveling the complexity of the extracellular vesicle landscape with advanced proteomics
Published in Expert Review of Proteomics, 2022
Julia Morales-Sanfrutos, Javier Munoz
A relatively new size-based EVs isolation method is asymmetric flow field flow fractionation (AF4). This technique does not require a stationary phase as the isolation takes place in a thin, flat, and narrow chamber with a semi-permeable ultra-filtration membrane at the bottom. EVs are resolved by the use of two perpendicular flows: a laminar flow that carries the sample through the separation chamber and a variable crossflow, which is responsible for the vesicular separation. One of the greatest advantages of this technique is its high-resolution with a large dynamic size separation range, which allows the fractionation of EV subpopulations. Using an optimized AF4, Zhang et al [43]. managed to identify two small exosomal subpopulations with distinct sizes and molecular properties (i.e. large exosome vesicles, Exo-L, 90–120 nm and small exosome vesicles, Exo-S, 60–80 nm) and discovered a novel and abundant population of non-membranous nanoparticles, named exomers (~35 nm). Despite being a powerful tool, AF4 also has its limitations. Due to the small working volumes, the yield is low and, therefore, it may not be practical for all studies, and some samples may need a pre-concentration step. In addition, it is not easy to implement, requiring specific instrumentation and trained personnel to customize and optimize protocols.(8) Microfluidics