Search results for "CHROMATOGRAPHY"

Spectroscopic and chromatographic study of the interaction of nonionic micelles with the aluminum-morin complex

1989

Abstract The interaction of the aluminum-morin system with different nonionic surfactants has been studied spectrophotometrically and by high-performance liquid chromatography. It has been found that ethylene oxide-propylene oxide condensate surfactants sensitize the spectrophotometric determination of aluminum with morin more than ethylene oxide condensate surfactants. Binding ratio parameters for the different surfactants with free morin have been also estimated from the analysis of chromatographic vacant peaks.

Characterization of totally chlorine-free effluents from kraft pulp bleaching III

1999

Abstract Chemical changes in the dissolved high-molecular-mass material from silver birch (Betula pendula) kraft pulp during the oxygen–alkali delignification stage (O) and the subsequent totally chlorine-free (TCF) bleaching sequence (X–Z–EOP–AZ–EP–S) were investigated by analytical pyrolysis (pyrolysis–gas chromatography/mass-sensitive detector (Py–GC/MSD)). In addition, the pyrolysis data were subjected to chemometric analysis, resulting in a rapid method for determining with reasonable accuracy, for example, the mass proportion of carbohydrates and lignin in the effluents from each of the treatment stages. The method was calibrated by chemical analysis on the same effluents.

Risk assessment of beauvericin, enniatins and fusaproliferin present in follow-up infant formula by in vitro evaluation of the duodenal and colonic b…

2014

Abstract In this study, 72 samples of follow-up infant formula of Spanish origin were analyzed for the presence of the mycotoxins beauvericin (BEA), enniatins (ENs) (A, A1, B, B1), and fusaproliferin (FUS). The samples analyzed were extracted three times with ethyl acetate and then the mycotoxins were identified and quantified using a liquid chromatography (LC) coupled to a diode array detector (DAD). The positive samples analyzed in this study were digested through a simulated gastrointestinal digestion model, which permit to simulate the physiological condition of the human gastrointestinal tract (duodenal and colonic compartments) in order to assess the bioaccessibility of the bioactive …

Monomeric vs. polymeric bonded iminodiacetate silica supports in high-performance ligand-exchange chromatography

1983

The synthesis of monomeric and polymeric bonded iminodiacetate-groups on silica supports is described. The polymeric support offers advantages over the monomeric, such as (i) preparation is much simpler, (ii) higher surface concentration of functional groups can be achieved without loss of efficiency and (iii) hydrolytic stability. Cu2+ loaded supports were examined for their kinetic performance, in particular for the C-parameter of the Knox equation, and for their hydrolytic stability. Calculation of the surface coverage shows that only a rather thin polymeric layer is formed; this is in agreement with the results of the kinetic performance. The retention of α-amino acids on the Cu2+ loade…

Identification of drying oils used in pictorial works of art by liquid chromatography of the 2-nitrophenylhydrazides derivatives of fatty acids.

2004

A new HPLC-UV-Vis method for identification of drying oils from binding media or protective film used in pictorial works of art prior to conservation or restoration is proposed. Chromophore derivatization of fatty acids released by hydrolysis of structural drying oils is studied. The derivatization reagent selected was 2-nitrophenylhydrazine with 1-ethyl-3-(3-dimethyl animopropyl)carbodiimide hydrochloride/pyridine as catalyst. This reaction was carried out using microwave heating. Mobile phase was methanol/water/n-propanol/acetic acid (80:14:5:1) running in isocratic mode. Absorbance was measured at 400nm. In these conditions, hydrazides of myristic, palmitic, oleic, and stearic acids were…

Stability in physiological saline of intravenous busulfan in a polyolefin pack

2008

Abstract Introduction Although it has been used orally, the variability in its absorption and the risk of causing vomiting has lead to a push towards the intravenous use of busulfan. This study looks at the stability of 60 mg of busulfan, in fixed volumes of 250 mL (0.24 mg/mL) and 500 mL (0.12 mg/mL) of physiological saline and different conservation conditions, in a new plastic pack made from polyolefin/polyamide laminates. Material and methods High-performance liquid chromatography with ultraviolet detection was used to determine the concentration of busulfan derivate with sodium diethyldithiocarbamate trihydrate. Stability was assessed for both concentrations; refrigerated and at room t…

Efficient synthesis of 2-bromo-1-[18F]fluoroethane and its application in the automated preparation of 18F-fluoroethylated compounds

2002

An efficient synthesis of 2-bromo-1-[18F]fluoroethane from commercially available 1,2-dibromoethane and its integration into an automated preparation device was developed for the routine synthesis of 18F-fluoroethylated compounds. The 1,2-dibromoethane was reacted with the [18F]fluoride/Kryptofix 2.2.2./carbonate complex in acetonitrile at 70 degrees C for 3 min resulting in 60-70% radiochemical yields. The crude reaction mixture was diluted with water, loaded on a LiChrolute EN-cartridge, eluted with acetonitrile and passed through an AluminaB-cartridge. This method provides 2-bromo-1-[18F]fluoroethane with 98% radiochemical purity and <0.1 micromol of 1,2-dibromoethane within 10 min, thus…

Hydrodynamic chromatography for characterization and purification of liposomes

1989

1982

A version of DSC technique is proposed which ensures good accuracy in comparing the melting behaviour of two apparently similar samples. The information is obtained in the form of comparative thermograms recorded during simulataneous melting of both samples. The method is applied to observe the influence of cooling conditions and annealing on melting behaviour of low-density polyethylene.

Membrane Lipid-Polypeptide Molecular Associations in Non Aqueous Solvent. Effect of Phosphatidylcholine Concentration and Temperature and their Influ…

1986

Abstract The use of an Ultrastyragel 500 A column for the study of interactions between phosphatidylcholine and gramicidin A in tetra-hydrofuran is described. Analysis of vacant peak has allowed to establish the influence that eluent lipid composition, concentration of injected gramicidin and temperature have on the interaction. At 20[ddot] C, for the assayed phospholipid concentration range (0.04 to 0.14 %, w/v), the lipid/polypeptide molar binding ratio, BR, varies from 1.3 to 6.9. An increase in temperature from 20 to 40[ddot] C causes a decrease in BR of about 20 %. On the other hand, the interaction releases some of the water bound to the lipid polar head, suggesting that the binding i…