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Methods and Equipment for Quality Control of Radiopharmaceuticals
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Rolf Zijlma, Danique Giesen, Yvette Kruiter, Philip H. Elsinga, Gert Luurtsema
Thin Layer Chromatography (TLC) is a chromatography technique based on a solid phase, like paper or silica-coated plates (stationary phase) and a mobile phase (liquid). The analysis is run by putting the TLC plate with the sample on the origin spot in a glass container containing a small layer of mobile phase. The mobile phase is moving upwards along the TLC plate until the liquid has reached the top. The compound and its impurities have different affinities and absorption to the stationary and the mobile phases. The technique is easy to perform and does not require dedicated equipment and, if combined with a reader or scanner (Figure 6.8a), the readout of the plate of paper is simple to determine the per cent of radiochemical purity and the radionuclide purity of the radiopharmaceutical. Typically, TLC takes only a few minutes. (See Figure 6.8b for a typical chromatogram.)
Approaches for Identification and Validation of Antimicrobial Compounds of Plant Origin: A Long Way from the Field to the Market
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Lívia Maria Batista Vilela, Carlos André dos Santos-Silva, Ricardo Salas Roldan-Filho, Pollyanna Michelle da Silva, Marx de Oliveira Lima, José Rafael da Silva Araújo, Wilson Dias de Oliveira, Suyane de Deus e Melo, Madson Allan de Luna Aragão, Thiago Henrique Napoleão, Patrícia Maria Guedes Paiva, Ana Christina Brasileiro-Vidal, Ana Maria Benko-Iseppon
Thin Layer Chromatography (TLC) is a qualitative technique that identifies groups of secondary metabolites by comparing their Retention factor (Rf) values with reference substances. The compounds are initially separated according to the affinity between the mobile phase (nonpolar solvent) and the stationary phase (e.g., silica or cellulose) (Akash and Rehman 2020; Kashid and Kadam 2021). At the end of the chromatography, chromogenic markers and excitation by UV light are used to demarcate classes of compounds. For example, Dragendorff’s reagent allows the detection of alkaloids, while Folin reveals polyphenols such as isoflavones. Coumarins are detected by marking in 10% potassium hydroxide and excitation in UV 365 nm (Braz et al. 2012; Vieira et al. 2008). TLC can be used as the first step of qualitative identification of complex compounds, being an inexpensive technique, which does not require sophisticated equipment or even laborious sample preparation (Klimek-Turek et al. 2017).
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
Chromatography was first used for the separation of leaf pigments. The operation of chromatography is based on the distribution of material between a stationary phase and a mobile phase. The stationary phase can be a solid or a liquid supported on a solid while the mobile phase can be a gas or a liquid, which flows continuously around the stationary phase. As a result of differences in their affinity for the stationary phase, the different components in a mixture can be separated and identified.
Toxoplasma gondii infection: novel emerging therapeutic targets
Published in Expert Opinion on Therapeutic Targets, 2023
Joachim Müller, Andrew Hemphill
A key step in the heuristic identification of targets of compounds issued from screening is the characterization of drug-binding proteins [48]. If we admit that a given compound uniquely or at least preferentially physically interacts with a given protein, affinity chromatography is the method of choice to identify such target proteins (Figure 2). The effective compound of interest is coupled to a suitable inert matrix. In parallel, an ineffective compound with high structural similarities to the effective compounds is coupled to the same kind of inert support. Columns filled with this material are inserted into a low-pressure liquid chromatography device. Cell-free extracts from organisms of choice are loaded into both columns in parallel. After suitable washing steps, bound proteins are eluted and identified by convenient proteomic tools. The proteomes identified in eluates from effective and ineffective compounds are compared. The differential affinoproteome, i.e. the subset of proteins binding to effective, but not to ineffective compounds, should then contain potential targets.
Dietary S. maltophilia induces supersized lipid droplets by enhancing lipogenesis and ER-LD contacts in C. elegans
Published in Gut Microbes, 2022
Kang Xie, Yangli Liu, Xixia Li, Hong Zhang, Shuyan Zhang, Ho Yi Mak, Pingsheng Liu
Bacterial lipid extraction, separation, and analysis were conducted as described previously.43 In general, bacteria were grown at 20°C on the NGM plates, after 24 h, 3 ~ 5 mg bacteria were collected into glass tubes and water was removed with a Pasteur pipet. To each bacterial pellet 1 ml of MeOH and 2.5% H2SO4 was added. Fatty acids were extracted and converted into methyl esters by heating at 70°C for 60 min. Then the extractions were incubated at 25°C for 5 min followed by addition of 0.2 ml of hexane and 1.5 ml of water. The mixtures were shaken vigorously and then centrifuged 12,000 g for 1 min in a clinical centrifuge. The fatty acid methyl esters contained in the top hexane-rich fraction were collected and 2 μl were analyzed using an Agilent 6890 series gas chromatograph equipped with a 20 m x 0.25 mm SP-2380 column (Supelco, Bellefonte, PA) and a flame ionization detector. The Gas Chromatography (GC) was programmed for an initial temperature of 120°C for 1 min followed by an increase of 10°C per min up to 190°C followed by an increase of 2°C per min to 200°C. Peak identity was determined by mass spectroscopy.
Chemical tools to monitor bladder cancer progression
Published in Biomarkers, 2022
Natalia Gruba, Lech Stachurski, Adam Lesner
There is no doubt that early cancer detection can ensure proper treatment and may save lives. For this reason, the search for new diagnostic methods, and thus specific and sensitive biomarkers, plays a significant role in the treatment of cancer. In 2011 Ali et al. (2011), presented the role of chromatography for the separation and identification of breast cancer biomarkers. The authors pointed out genetic, proteomic, metabolic and breath ones. They indicate that chromatography is of the greatest importance and future among many detection techniques. Four years later, Al Za'abi et al. (2015, 2016) presented the use of chromatographic techniques, spectrometry and nanotechnology in the detection of acute kidney injury biomarkers. As indicated the efforts of scientists focus on both, the search for new biomarkers, as well as appropriate methods of their detection, especially at low concentrations and tiny biological samples.