Search Results

You are looking at 1 - 10 of 34 items for :

  • "gel permeation chromatography" x
  • Refine by Access: All Content x
Clear All

This paper develops an instrumental analytical approach for detection of fourteen polycyclic aromatic hydrocarbons (PAHs) in edible oil samples using gel permeation chromatography (GPC) and ultra-high performance liquid chromatography (UHPLC) coupled with diode array detector (DAD), and fluorescence detector (FLD). The GPC was used to remove triglycerides from edible oil samples. The extracted samples were then detected using UHPLC—DAD—FLD. In order to obtain good separation and high reproducibility, the UHPLC—DAD—FLD experimental condition was optimized. The PAHs including three groups of isomeric PAHs can be separated completely in 12 min using BEH Shield RP 18 column with a suitable gradient elution program. The mean recoveries were in the range of 73–110% with an acceptable reproducibility (RSD < 10%, n = 3). During real sample analysis, the method can decrease the chance of false positives with both DAD and FLD being used simultaneously. The results indicate that the approach is simple, easy, and acceptably reproducible, thereby showing great potential as a method for detection of fourteen PAHs contained in edible oil samples.

Open access
Journal of Thermal Analysis and Calorimetry
Authors: C. Ramírez, M. Rico, J. M. L. Vilariño, L. Barral, M. Ladra, and B. Montero

Summary Cubic silsesquioxanes offer access to organic/inorganic hybrids. A system formed by a polyhedral oligomeric silsesquioxane (POSS) with eight epoxy reactive groups per molecule, octaepoxycyclohexyldimethylsilyl-POSS, cured with an aliphatic diamine (bisaniline) was studied in different ratios. The characterization of the POSS was carried out by differential scanning calorimetry (DSC) and thermogravimetry (TG). The distribution of species in the reaction of the mixtures POSS/diamine was followed by gel permeation chromatography (GPC). The degradation was studied by thermogravimetric analysis.

Restricted access

to avoid further crystallization during storage. The molecular weights of prepared specimens are measured using gel permeation chromatography (GPC) at 25 °C. GPC is consisted of columns of PLgel 5 μ 10000 A, 5 μ Guard, and 5 μ Mixed-C from

Restricted access

. Gel permeation chromatography (GPC) Gel permeation chromatography (GPC) (Waters, with RI detector) was used for discerning if there were changes in molecular weights caused by thermal degradation and/or molecular interactions between the

Restricted access

Abstract  

Tracer110mAg has been used to investigate the speciation of silver in natural waters, which may contain chloride, sulphide or humate ions. Silver chloride or oxide is readily absorbed from waters by many materials, and some may be photochemically reduced to metallic silver. Absorbed silver, silver chloride and silver sulphide may be distinguished by their desorption behaviour. Humates form complexes with silver chloride, silver sulphide and the silver cation, which can be separated from smaller species by gel permeation chromatography.

Restricted access

Abstract  

Vanadium in marine organisms from Onagawa Bay in Miyagi, Japan, was determined by an instrumental neutron activation analysis (INAA) method using anti-coincidence gamma-ray spectrometry at the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility in Canada. Seaweeds, cultivated oysters, plankton, and four different species of sea squirt were collected from Onagawa Bay during 2005–2008. Vanadium levels around 20 μg g−1 (dry weight) were found in Japanese tangle and hijiki seaweeds. One species of sea squirt (Ciona savignyi) contained 160–500 ppm of V and it was highest among the four species of sea squirts studied. Protein-bound V species were separated by gel permeation chromatography (GPC) and the element determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).

Restricted access

Commercial sodium caseinate isolate (SCI) was hydrolysed with either protease Subtilisina carlsberg - Alcalase 2.4 FG (purchased from Novo Nordisk), pronase from Streptomyces griseus, and papain EC 3.4.22.2 (both from Sigma) in a two-step process to determine the changes in the immunoreactivity of a-, ß- and ?-casein. Enzymatic hydrolysis of SCI was performed by pH-stat method. Hydrolysates were analysed using IEF, SDS-PAGE, 2D electrophoresis, FPLC-gel permeation chromatography. Immunoreactive properties of peptide fractions separated from the hydrolysates by FPLC were determined using dot-immunobinding and ELISA methods. The two-step process was observed to be effective in reduction of casein fractions immunoreactivity, however, allergenic epitopes were still present in all peptide fractions.

Restricted access

A new bacterial strain, capable of degrading poly(3-hydroxybutyrate) (PHB) was isolated from soil. This organism, identified as Streptoverticillium kashmirense AF1, secreted PHB depolymerases both on solid as well as in liquid mineral salt medium containing poly(3-hydroxybutyrate) as sole carbon source. The optimum production of PHB depolymerase was observed at pH 8 and 7, at 45 °C, 1% substrate concentration and in the presence of lactose as an additional carbon source. The extracellular PHB depolymerase was purified by gel permeation chromatography using Sephadex G-75. The Streptoverticillium kashmirense AF1 produced two types of PHB depolymerases having molecular weights of about 37 and 45 kDa as determined by SDS-PAGE. The difference in dry cell mass and amount of CO 2 evolved in the test and control calculated gravimetrically through Sturm test indicated the degradative capabilities of Streptoverticillium kashmirense AF1.

Restricted access

Abstract  

In the present study, the characteric-structure relationship of epoxidized soybean oils (ESO) with various degrees of epoxidation has been investigated. FTIR analysis was used to identify the relative extent of epoxidation of the samples during the epoxidation reaction. The viscosities of ESO were much higher than that of the raw oil, viscosity increased with degree of epoxidation. The viscous-flow activation energy of ESO was determined to be higher than that of the raw oil (20.72 to 77.93% higher). Thermogravimetry analysis (TG) of ESO was used to investigate the thermodynamic behavior of the samples. With increasing degree of epoxidation, the thermal stability of the samples initially decreased, then increased at the final reacting stage. Differential scanning calorimeter (DSC) indicated that the melting point of ESO was higher than that of soybean oil. Gel permeation chromatography (GPC) indicated the molecular mass of the samples increased initially, then decreased, with an increase in the extent of epoxidation.

Restricted access