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Hyper-crosslinked Polymers
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Porous Polymer Science and Applications, 2022
Belén Arcentales-Vera, Lisandra Bastidas, Moises Bustamante-Torres, Paul Maldonado Pinos, Emilio Bucio
SEC is a technique used for separating substances according to their molecular size or hydrodynamic volume (Moldoveanu and David 2013). It can be used to measure both the size and the polydispersity of a synthesized polymer; that is, it can find the distribution of the sizes of polymer molecules (Giridhar, Manepalli, and Apparao 2017). Moreover, ISEC determines the PSD of a column packing material by monitoring the residence times of solutes of varying molecular diameters (Goto and McCoy 2000).
Liquid Chromatography
Published in Ernő Pungor, A Practical Guide to Instrumental Analysis, 2020
To get molecular weight information from the measured value of elution volume we know the relationship between KSEC and the molecular weight. The separation in SEC depends on the molecular sizes and not the molecular weight. The size of a molecule in a solution depends on the solvent used. Biopolymers have different conformation in different solvents (ionic strength, pH) and the retention as well.
Downstream Processing
Published in Maik W. Jornitz, Filtration and Purification in the Biopharmaceutical Industry, 2019
Resins are available which separate molecules within particular size ranges (Table 15.3). SEC is therefore used for the fine fractionation of molecules by size in the same way that gel electrophoresis exploits the sieving potential of agarose and polyacrylamide gels. Indeed, many of the SEC media available commercially are based on agarose, polyacrylamide, and other polymers. An important concept in SEC is that the separation medium is the pores on the beads and not the beads themselves. Therefore, 95%–99% of the column volume remains unused in any operation, and feed volumes must be adjusted accordingly, representing a significant bottleneck. For this reason, SEC is often the very final stage in biopharmaceutical purification, and is used to separate the target protein from very similar molecules such as degradation products and multimers. The most important variables in SEC are the column length and linear flow rate. Slow mass transfer of macromolecules can cause peak broadening and loss of resolution, which can be addressed by reducing the flow rate.
Lactose hydrolyzed milk powder: Thermodynamic characterization of the drying process
Published in Drying Technology, 2018
Tatiana Lopes Fialho, Evandro Martins, Arlan Caldas Pereira Silveira, Carolina Rodrigues de Jesus Silva, Ítalo Tuler Perrone, Pierre Schuck, Antônio Fernandes de Carvalho
By reducing the inlet air temperature, a decrease in the SEC value could be observed (Fig. 4b). It seems that for low flow rates (<1.0 kg h−1), the inlet air temperature is the principal factor that determines the SEC value. The temperature reduction conducts to a decreasing in the inlet total energy (εtotal,in), which directly reduces the SEC value.[18]