Search results for "Adsorption"
showing 10 items of 1326 documents
Clay-biosurfactant materials as functional drug delivery systems: Slowing down effect in the in vitro release of cinnamic acid
2017
Abstract The main objectives of the present paper were the preparation and characterization of new surfactant-modified clays and the evaluation of their potential applicability as drug delivery systems for the oral administration of the cinnamic acid (CA) drug. The organoclays (OC) were prepared by loading different amounts of the biocompatible nonionic polyoxyethylene sorbitan monolaurate surfactant (Tween20) onto K10 montmorillonite (Mt) clay and characterized through the construction of the adsorption isotherms by means of the spectrophotometric method. The performance of the prepared material was verified by gathering the adsorption isotherms of the cinnamic acid onto the Mt/Tween20 org…
Sulphonic acid strong cation-exchange restricted access columns in sample cleanup for profiling of endogeneous peptides in multidimensional liquid ch…
2006
Abstract In this work, the pore structural parameters and size exclusion properties of LiChrospher strong cation-exchange and reverse phase restricted access materials (RAM) are analysed. The molecular weight size exclusion limit for polystyrenes was found to be about 17.7 kDa, while for standard proteins, the molecular weight size exclusion limit was higher, at approximately 25 kDa. The average pore diameter on a volume basis calculated from the pore network model changes from 8.5 nm (native LiChrospher) to 8.6 nm (diol derivative) to 8.2 nm (sulphonic acid derivative) to 6.9 nm ( n -octadecyl derivative). Additional characterisations were performed on restricted access materials with nitr…
Column technology in liquid chromatography
2017
This chapter deals with the most important part of the liquid chromatography (LC) system: the column enabling the efficient and fast resolution of complex mixtures. It is divided into seven sections under the overall aspects of manufacture, operation, and evaluation of analytical columns for the user. The first three sections highlight the column design and hardware, followed by a thorough treatment of the properties of microparticulate silica adsorbents as packing material, stationary phases performed by surface functionalization, and the column filling process. Then, the implementation of the column into the LC system is discussed, leading into chromatographic column testing as a C18-bond…
Complete decontamination and regeneration of DNA purification silica colum
2008
Silica columns are among the most used DNA purification systems, allowing a good yield of high-quality nucleic acids without organic extractions. Silica column regeneration protocols reported up to now to remove DNA traces are time-consuming, and their effectiveness on genomic DNA has not been demonstrated. Here we report a very rapid regeneration procedure that ensures no DNA carryover, independent of its size, without impairing column efficiency. The method takes advantage of the improved DNA removal by low concentrations of Triton X-100.
Quantitative retention–structure and retention–activity relationships of barbiturates by micellar liquid chromatography
1998
Abstract Studies on the structural requirements of chromatographic surfaces to emulate in vitro the partitioning process in biomembranes are of great interest. The use of micellar mobile phases in RPLC modifies the hydrophobicity of the stationary phase and provides hydrophobic and electrostatic sites of interaction as a consequence of the adsorption of surfactant monomers to the chromatographic surface. Modified stationary phases in MLC could be structurally similar to biomembranes, but thorough studies are necessary to confirm this. In this paper we focus our attention on barbiturates. The influence of the nature and concentration of the surfactant (Brij 35, SDS and CTAB) and the mobile p…
Solid-Phase Extraction of Organochlorine Pesticides from Water Samples
1990
Abstract A procedure for the accumulation of organochiorine pesticides by reversed-phase adsorption on octadecylsilica glass microcolumns was used for the isolation and concentration from spiked distilled and natural waters. The pesticides were eluted from the octadecylsilica with light petroleum, and analyzed by gas chromatography using an electron capture detector. The average recovery was over 90% in spiked water samples at 0.1 ng/ml. The performance of the octadecylsilica when applied to the analysis of water samples were compared with the Rodier and the APHA solvent extraction methods.
Study of conformational effects of recombinant interferon gamma adsorbed on a non-porous reversed-phase silica support.
1995
Abstract Reversed-phase chromatography is a powerful method for separating recombinant interferon γ and one of its analogues differing only by a single amino acid residue. Structural differences of the proteins explain this separation ability as demonstrated from adsorption studies on a non-porous reversed-phase support. To reveal the structural differences occurring in the adsorbed state, two different and independent methods were employed. The variation of the retention with the slope of the linear gradient gave information about the molecular contact area of the protein with the support. For different experimental conditions, these data were correlated with the adsorbent capacities measu…
Aerobic granular sludge treating shipboard slop: Analysis of total petroleum hydrocarbons loading rates on performances and stability
2018
Abstract The work focuses on the feasibility of treating slop with aerobic granular sludge. For this purpose, a 3.5 L granular sequencing batch reactor was activated and it was monitored for 156 days. The experimental campaign was divided into two periods, named Period I (100 days) and Period II (56 days). Total Petroleum Hydrocarbon (TPH) concentration in the slop was, on average, equal to 6.8 ± 1.5 mg L−1 and 13 ± 1.5 mg L−1 in Period I and Period II respectively. The obtained results during the first experimental period indicated that about 80 days were required to reach steady state with mature granules, when TPHs removal efficiency was approximately 90%. The results indicated that both…
Cultivation of granular sludge with hypersaline oily wastewater
2015
The time required to stabilise mature aerobic granules is rather variable. In addition, cultivation time and the structural characteristics of granules seem to be related to the nature of wastewater influent. Granular sludge has been used for the treatment of several industrial wastewaters, but nothing has been reported about wastewater characterized by the simultaneous presence of hydrocarbons and high chloride concentration. In this work, the authors analysed the granulation process and performance as well as the physical characteristics of aerobic granules in two Granular Sequencing Batch Airlift Reactors (GSBARs), fed with acetate-based synthetic wastewater in reactor 1 (R1) and with a …
Supercritical Fluid Adsorption of Domperidone on Silica Aerogel
2013
Silica aerogel (SA) was loaded with domperidone to demonstrate the potentiality of adsorption processes based on the usage of supercritical carbon dioxide to treat poorly water-soluble drugs, forming new kinds of drug delivery systems. The effects of pressure, temperature and solution concentration on loaded SA were studied. Adsorption isotherms were measured at 35℃ and 45℃ and fitted with Langmuir model. Release kinetics of the adsorbed drug were also evaluated by in vitro dissolution tests. Results showed that domperidone can be uniformly dispersed into the aerogel and that the release rate of domperidone from the composite, constituted by drug and silica aerogel, is much faster than that…