Search results for "Extraction"
showing 10 items of 2072 documents
Simultaneous isolation of xanthomegnin, viomellein, rubrosulphin, viopurpurin, and brevianamide A by preparative HPLC.
1984
A method for the isolation of xanthomegnin, viomellein, rubrosulphin, viopurpurin, and brevianamide A from Penicillium viridicatum (DSM 2447) is described. After extraction, HPLC was performed with a preparative silicagel column, eluted with toluene / ethyl acetate / formic acid (27/9/1, v/v/v) and dichloromethane / acetic acid (9/1, v/v). The toxins were detected with a UV-monitor. It was possible to isolate them in an absolutely pure state. The described method is operationally simple and very efficient.
Evaluation of extraction alternatives for Fourier transform infrared spectrometric determination of oil and greases in water
1997
Abstract Liquid-liquid extraction (LLE), solid phase extraction (SPE) and microwave-assisted extraction are evaluated for Fourier transform infrared (FTIR) spectrometric determination of oil and grease in polluted waters. A fast microwave-assisted quantitative procedure is proposed for the total extraction of oil and grease into CCl 4 from water samples, with an irradiation time of 1 min at an exit power of 520 W using closed PTFE vessels. The FTIR quantification of oil and grease is carried out by the measurement of the area under the absorbance spectra in the range between 3058 and 2780 cm −1 , with a baseline established between 3200 and 2700 cm −1 . The analytical features of the propos…
Profiling of endogenous peptides by multidimensional liquid chromatography: On-line automated sample cleanup for biomarker discovery in human urine.
2009
A simple and flexible system, employing a column switching technique, has been designed to allow the analysis of peptides and proteins smaller than 15 kDa by molecular weight in filtered urine samples by performing a direct on-column injection utilising simultaneous sample clean-up and trace enrichment. The positively charged peptides and small proteins in the sample are attracted to the inner, negatively charged pore structure of the RAM-SCX column while the larger proteins and uncharged or negatively charged compounds are excluded. After preconditioning with the biological sample, large amounts of sample can be injected. Several important and adjustable parameters for the proper use of a …
Liquid chromatographic determination of aliphatic amines in water using solid support assisted derivatization with 9-fluorenylmethyl chloroformate
2002
A simple and sensitive method has been developed for the liquid chromatographic determination of short-chain aliphatic amines in water. Analytes are retained in solid-phase extraction (SPE) cartridges, and then derivatized by drawing an aliquot of the fluorogeneic reagent 9-fluorenylmethyl chloroformate (FMOC) through the cartridges. After a certain reaction time the derivatives formed are desorbed with acetonitrile. The collected extracts are then chromatographed on a LiChrospher 100 RP18 125 mm×4 mm i.d., 5 μm, column using an acetonitrile-water gradient. The influence of experimental conditions (SPE material, volume of sample, concentration of FMOC, time of reaction and pH) has been inve…
Determination of organic contaminants in food by capillary electrophoresis
2005
This review addresses recent advances in the analysis of organic contaminants, such as antibiotics, pesticides, biological toxins, and food-borne pathogens, in foods by capillary electrophoresis (CE). Special attention is paid to those aspects that increase sensitivity and/or selectivity, such as sample extraction and concentration, on-line preconcentration techniques (stacking), affinity capillaries or/and specific detectors (laser induced fluorescence (LIF), mass spectrometry (MS)). The various CE modes used to separate the compounds and the quantification strategies are also examined. As a result, this work presents an updated overview on the principal applications of CE, together with a…
Current methodologies for phytosterol analysis in foods
2021
Abstract Plant sterols (PS) (phytosterols and phytostanols) are bioactive compounds of all vegetable foods where can be found as free sterol alcohols and as conjugates. These latter forms have been less studied, although they may have potential beneficial effects, whereas some PS have several approved health claims, especially in lowering blood cholesterol levels. In this context, it is necessary to establish analytical methods for food authentication, assessing PS health benefits and unfolding future applications. Several extraction methodologies have been employed for the extraction of PS from food matrixes (usually solvent extraction and saponification) although solid-phase extraction, s…
Analysis of phytosterols in foods
2006
Phytosterols are bioactive compounds, one of their most studied and outstanding properties being their cholesterol-lowering activity. This explains the growing interest in the phytosterol contents of foods as either intrinsic or added components. The different steps (extraction, saponification, clean up, chromatographic determination) of plant sterol determination are reviewed, and emphasis is placed on the methods used to assay different phytosterols in food.
Purification and identification of a cytokinin from moss callus cells.
1976
A cytokinin was isolated from the culture medium of callus cells of the moss hybridFunaria hygrometrica (L.) Sibth xPhyscomitrium piriforme Brid. The purification procedure included ethyl-acetate extraction, silver-salt precipitation, crystallization as picrate, and ion exchange chromatography. The structure of the cytokinin was confirmed as N(6)-(Δ(2)-isopentenyl)adenine by means of gas chromatography and mass spectrometry. The concentration of the compound in the culture medium was determined at ca. 10(-6) M.
Beiträge zur Extraktion von Drogen. 4. Mitt.: Selektive Extraktionseigenschaften von Lösungsmitteln
1969
Am Beispiel der getrockneten Meerzwiebel wird gezeigt, wie bei der fraktionierten Extraktion mit Losungsmitteln steigender Polaritat die gewunschten Extraktivstoffe bis zu einem gewissen Grad selektiv extrahiert werden konnen. Extraction of Vegetable Drugs With the squill as example it is shown that the components of the extractable matter can be extracted selectively up to a certain point in a fractioned extraction with solvents of increasing polarity.
Supercritical fluid extraction of pesticides
1989
The extraction behaviour of 10 μg samples of five pesticides and some related compounds from glass wool with supercritical CO2 has been investigated under several conditions (10 MPa, 20 MPa extraction pressure, 313 K, dry and water saturated CO2). The extraction fluid was decompressed over a line of little columns, filled with 3μ Si60 or RP18, and the amount of deposited material was analyzed by HPLC for each of these columns. Due to the progressive pressure/density reduction along the line, the solubility diminishes and hence the compounds are deposited according to their polarity/vapor pressure earlier or later on the line. Thus extraction and prefractionation of compounds of different po…