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Role of Different Bioreactor Types and Feeding Regimes in Polyhydroxyalkanoate Production
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Geeta Gahlawat, Sujata Sinha, Guneet Kaur
Polyhydroxyalkanoates (PHA) are considered to be the future of bioplastics, which have similar processing and material properties as conventional plastics (e.g. propylene), and can undergo processing extrusion, injection and molding [1]. These can be easily broken or decomposed by soil microbes and are understood to be completely biodegradable in nature. Industrially synthesized PHA have the potential to have a wide range of applications such as (a) pharmaceuticals: controlled release and in drug delivery systems; (b) biofuel: methyl ester of 3-hydroxybutyrate and other 3-hydroxyalkanoates are used as biofuel; (c) medicine: absorbable sutures, pin, film and staples, plates of bones, implants, grafts in tissue engineering, (d) disposables like food trays, diapers, razors, utensils, cosmetics packaging, glasses, carpet, compostable lids, etc. (e) chromatography: in chromatography columns they may be used as stationary phase; (f) agriculture: in regulated discharge of pesticides, herbicides, fertilizers and plant growth regulators [2].
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.
High-Performance liquid Chromatography
Published in John V. Twork, Alexander M. Yacynych, Sensors in Bioprocess Control, 2020
The chromatographic process is based on the fact that the individual components of a sample mixture, under identical conditions, are distributed to different extents between two phases, stationary and mobile. The stationary phase is a fixed bed of solid particles which may or may not be covered with a liquid coating. The mobile phase, or carrier, is a fluid medium that transports the sample mixture past the fixed bed or stationary phase. As the mobile phase permeates through the stationary phase, components that are more soluble or have greater affinity for the stationary phase move through the column at a slower rate than those components that favor solubility in the mobile phase. The net effect is that the various components are separated into individual elution bands for analysis.
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]
A critical review of separation technologies in lignocellulosic biomass conversion to liquid transportation fuels production processes
Published in Chemical Engineering Communications, 2022
Paola Ibarra-Gonzalez, Lars Porskjaer Christensen, Ben-Guang Rong
In column chromatography, the substances are separated based on their different adsorption capabilities on a stationary phase. Regularly, as the stationary phase, silica gel is employed, and depending on the polarity of the components in the mixture, an eluent is selected (Wang 2013). Li et al. (2005) performed the separation of bio-oil from fast pyrolysis via liquid chromatography. For its separation, a silica gel column was employed, in which the bio-oil was washed down using different solvents like cyclohexane, benzene and methanol. The fractions obtained from the separation were analyzed by GC-MS. The results showed that aromatics with up to four rings predominated in the first fraction, one ring aromatics in the second fraction and polar compounds were found in the third fraction. Moreover, it was found that chemicals like phenol and naphthalene and methyl-naphthalene are produced from lignin and cellulose, respectively (Li et al. 2005).
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.