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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
To determine the radiochemical purity, the chemical purity, and to calculate the molar activity, a High-Performance Liquid Chromatography (HPLC) system combined with an online radioactivity (RA) and-UV detector are needed. HPLC is standard lab equipment, and its performance depends on the selection of the columns and choice of the detector. A high pressure HPLC pump pushes the mobile phase through an HPLC-column. As described for TLC, the analysis of the radiopharmaceutical is based on different affinities of the components in the sample for either the stationary or mobile phase. The higher the affinity for the stationary phase, the longer the component will remain on the column. The time it takes for a component to elute from the HPLC-column is called retention time. Typically, an HPLC-analysis takes 5–20 min. In terms of radiochemical and chemical purity, two different detectors are required: One to measure the mass, most often with a UV detector, and a second online radioactivity detector (Figure 6.11). The ratio between the measured radioactivity and the calculated mass reflects the molar activity of the desired compound. Although UV detection is quite standard, electrochemical detection (ECD) is also used in radiopharmaceutical analysis. The ECD is more sensitive than UV detection for molecules with electroactive functional groups such as amine or phenols [7].
Mobile Phase Effects in Reversed-Phase and Hydrophilic Interaction Liquid Chromatography
Published in Nelu Grinberg, Peter W. Carr, Advances in Chromatography Volume 57, 2020
In high-performance liquid chromatography, the stationary phase is usually a bed of fine solid particles with narrow size distribution, densely packed in a metal, glass or plastic tube – a chromatographic column. The particles may be either fully or only partially porous, such as core-shell columns with a layer of the stationary phase chemically bonded to a support material. On the contrary, monolithic columns do not contain particles; instead, a continuous chromatographic bed fills the full inner column volume. The mobile phase (eluent) is a liquid, usually a mixture of two or more solvents (often containing suitable additives) forced through the column by applying elevated pressure in HPLC. The sample compounds move at different velocities along the column, together with – but more slowly than – the mobile phase. The elution process ideally leads to the eventual sample separation. The separated compounds appear at different times at the outlet from the column as the elution waves (peaks) monitored by a detector attached to the outlet of the column. The elution (retention) time, tR, of the peak maximum is a characteristic property of each sample compound, depending on the distribution constant between the stationary and the mobile phases in the chromatographic column. Hence, the tR, or the retention volume VR, is a useful tool for solute identification.
Chromatography
Published in Pau Loke Show, Chien Wei Ooi, Tau Chuan Ling, Bioprocess Engineering, 2019
Kirupa Sankar Muthuvelu, Senthil Kumar Arumugasamy
The components of HPLC include a reservoir, pump, injector, mixer, the column, and a detector or recorder. These components are interconnected in series via a steel tube (Figure 6.16). The pump is meant for controlling the flow rate of solvent through the system. With the controlled flow rate, the solvent reaches the injector. Then, along with the injected sample, it travels through the column and finally reaches the detector or recorder. The injector limits the volume of sample to be injected and thus creates a convenient flow of sample onto the column. The detector identifies the particular analyte and displays it as a peak. Finally, the sample, along with the solvent, elutes or leaves the column. The separated components are fractionated individually after collection in a fraction collector for further analysis (Zotou, 2012). The retention time and the peak area in the chromatogram are the two significant parameters to understand about each analyte. Figure 6.17 shows the chromatogram of diet soft drinks. Figure 6.18 shows the large surface area particles of silica (the stationary phase in HPLC) that have a “greasy” coating on the surface.
Production and purification of fucoxanthins and β-carotenes from Halopteris scoparia and their effects on digestive enzymes and harmful bacteria
Published in Environmental Technology, 2023
Farah Hadjkacem, Jihen Elleuch, Guillaume Pierre, Imen Fendri, Philippe Michaud, Slim Abdelkafi
HPLC was used to confirm the purity of fucoxanthin and β-carotene fractions after column chromatography purification and TLC analysis. The HPLC system includes an LC-20AT pump system, a UV-Vis SPD-20A absorption detector, and online Analysis Software. A Luna 5 M C 18 (4.6 mm 250 mm, 5 μm particle size, Phenomenex, Torrance, CA, USA) reversed-phase column was used for separation. For fucoxanthin elution, pure methanol was used as mobile phase at a flow rate of 1 mL/min. For β-carotene elution chromatographic separation was performed using gradient elution with a tertiary mobile phase of MeOH-10 mM ammonium acetate, MTBE (100%), and water (100%) set in reservoirs A, B, and C, respectively. Separations were performed by the following solvent gradient: 0–24 min 83% A, 15% B and 2% C; 24–32 min 63.5% A, 35% B, and 1.5% C; 32–34 min 33.5% A, 66% B, and 0.5% C; and 35 min 83% A, 15% B, and 2% C. The injection volume was set at 20 µL at 28°C and the detection wavelength for the two pigments was adjusted to 450 nm. Before injection, all samples were filtered using a 0.22 μm filter. Pure fucoxanthin and β-carotene standards were dissolved in methanol at concentrations of 0.125 µg/ml in pure methanol were used as an internal standard [29].
Polycyclic aromatic hydrocarbons in aquatic animals: a systematic review on analytical advances and challenges
Published in Journal of Environmental Science and Health, Part A, 2022
Ivelise Dimbarre Lao Guimarães, Francielli Casanova Monteiro, Júlia Vianna da Anunciação de Pinho, Paloma de Almeida Rodrigues, Rafaela Gomes Ferrari, Carlos Adam Conte-Junior
Chromatographic methods are used to separate target analytes from co-extracted interferences in samples and can be divided into two main categories: GC and HPLC. GC is the technique of choice for organic compounds, which can be volatilized without being decomposed or chemically rearranged. HPLC is a useful separation technique for semi-volatile and nonvolatile chemicals or for analytes that decompose on heating. Successful liquid chromatography separation requires the analyte(s) of interest to be soluble in the solvent(s) selected as the mobile phase. Chromatographic methods achieve separation by passing a mobile phase through a stationary phase. The mixture constituents are separated by the difference in elution over the stationary phase with different retention times. The compounds that interact strongly with the stationary phase elute slowly (longer retention times), while compounds that remain in the mobile phase elute rapidly (shorter retention times).[13,23,24]
An overview of simultaneous saccharification and fermentation of starchy and lignocellulosic biomass for bio-ethanol production
Published in Biofuels, 2019
HPLC can be used for quick and efficient separation and detection of ethanol in a sample. HPLC consists of solvent reservoir, pump, injector port, column, detector and waste reservoir. The ethanol containing sample is first injected into the injector. The different components in the mixture pass through the column at different rates due to differences in their partitioning behavior between the mobile liquid and the stationary phase. Resin (stationary phase) in the column is what aids in the separation. After separation, a detector report helps to detect how much he ethanol present in the sample by the integration of produced spectra. For detection by HPLC, the sample is collected in a sterile syringe and pushed into a 15 ml centrifuge tubes with screw cap. Then the sample is centrifuged at 8000 rpm at 4 °C for 10 min. After centrifugation, the liquid part can decanted to another centrifuge tube. This liquid part can be further filtered through a 0.2 micrometer filter and stored at -20°C and finally processed for analysis by HPLC.