Search results for "SAMPLE"

Determination of water-soluble vitamins in energy and sport drinks by micellar electrokinetic capillary chromatography

2016

Abstract A method for the determination of water-soluble vitamins in several energy and sport drinks by micellar electrokinetic chromatography (MEKC) has been developed in this work. The separation of vitamins was studied in terms of background electrolyte composition (borate content, pH, surfactant type and content) and in other MEKC parameters. A study of the possible compounds found in the vitamin-enriched drinks that could interfere in vitamin determination was also performed, and a modified procedure with enhanced resolution was developed. The proposed method was successfully applied to the analysis of water-soluble vitamins in a variety of energy and sport drinks and also in fruit nec…

Solubility of some pesticides in supercritical CO2

1988

The solubility limits of some pesticides (Linuron, Methoxychlor, Diclofopmethyl, Diclofop and 2,4-D) and of 3,4-dichloroaniline have been determined in supercritical CO2 at 200 bar and 40° C, using the Milton Roy sample preparation accessory SPATM. Depending on the polarity and vapour pressure of the investigated compounds, the solubility was found to be between 0.3 and 12 gl−1.

Supercritical Fluid Extraction and Supercritical Fluid Chromatography of Vitamin E in Pharmaceutical Preparations

1999

Peptides analysis in blood plasma using on-line system of supported liquid membrane and high-performance liquid chromatography

2005

The potential of using supported liquid membrane (SLM) technique, combined with reversed-phase high-performance liquid chromatography (RP-HPLC) has been investigated for the determination of peptides in human blood plasma. The peptides studied were (DL)Leu(DL)Phe, MetLeuPhe, GlyLeuTyr and ValGluProlleProTyr. The carrier (Aliquat 336) was incorporated in membrane phase in order to facilitate the transport of investigated peptides. After extraction, the analyte-enriched acceptor phase was directly injected into an HPLC system for analysis. With SLM, high selectivity and efficiency were achieved for extraction of peptides in aqueous solutions. Lower extraction efficiency was obtained in plasma…

Botanical Origin Authentication of Polish Phacelia Honey Using the Combination of Volatile Fraction Profiling by HS-SPME and Lipophilic Fraction Prof…

2019

Eleven samples of Polish Phacelia tanacetifolia Benth., three Brassica napus and one Salix spp. honeys were characterized by melissopalynology and analysis of the compositions of their volatile fractions. Headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME/GC–MS) using PDMS/CAR/DVB fiber was used for the isolation of low-molecular weight compounds which create a volatile fraction. To differentiate and indicate the most representative unifloral samples, chemometric techniques such as principal component analysis (PCA) and hierarchical-tree clustering (HTC) were applied to the dataset of the chromatographic fingerprints. Based on the obtained resul…

Erfassung niedriger Legionellen-Konzentrationen in Badebeckenwasser

2001

The Legionella proof is necessary in pool water according to DIN 19 643 in case of possible aerosol formation. In lab tests it was proven that the direct spatulation of 1 ml water offers high-grade proof with high correlation of the determined concentration to the actual germ content. With very small germ concentrations, however, preceding filtration of larger sample volumes is necessary. During the investigation of routine samples a Legionella proof was possible thereby in individual cases, whereas direct spatulation remained negative.

A LC/MS/MS method for the simultaneous quantification of free and masked fumonisins in maize and maize-based products

2008

An LC-ESI-MS/MS method for the simultaneous detection of the main fumonisins and their hydrolysed derivatives is described, allowing for a simplified sample preparation without previous clean up. The method has a very low quantification limit (10 µg/kg for FB1, 12 µg/kg for FB2 and FB3, 70 µg/kg for HFB1, HFB2 and HFB3 in maize flour) and a very good recovery for all the analytes. The method has been applied to check several maize-based foods for the presence of free and bound forms of fumonisins, the latter being determined after alkaline hydrolysis as hydrolysed derivatives. Bound fumonisins were found to be present not only in thermally treated maize-based products but also in mild proc…

Comparison of spectrophotometric and HPLC methods for determining sialic acid in infant formulas

2011

Abstract Two methods for determining sialic acid in infant formulas – spectrophotometry and HPLC with fluorescence detection – have been optimised and validated, the first one allows to determine total sialic acid while the second allows to differentiate the two main forms of sialic acid (N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc)). A common sample preparation procedure (hydrolysis and purification) for both methods has been proposed. The linearity (from 6 to 150 μg of total sialic acid in the assay for spectrophotometry, and from 12.5 to 250 ng and 1 to 5 ng of Neu5Ac and Neu5Gc, respectively, for HPLC) is adequate. The detection and quantification limits (0.29…

HPLC study on the ‘history’ dependence of gramicidin A conformation in phospholipid model membranes

1989

AbstractA novel HPLC methodology for the study of gramicidin A reconstituted in model membranes has been tested in comparison with circular dichroism data. It is shown that this chromatographic technique not only corroborates most of the recent spectroscopic results but allows one to explain them in terms of mass fractions of different actual conformational species of GA in the phospholipid assemblies. In particular, the dependence of the inserted peptide configuration on the organic solvent and other parameters involved in the ‘history’ of the sample preparation and handling has been analyzed by HPLC in two phospholipid model systems: small unilamellar vesicles and micelles. Moreover, a sl…

Methods of Digital Hilbert Optics in the Analysis and Objects’ Recognition

2016

This paper describes methods on how to increase the effectiveness of objects’ pictures identification based on correlation methods. The main concept of increasing the discriminant effectiveness is based on highlighting of characteristic points of recognized objects by applying Hilbert transformations. Study of the effectiveness of Digital Hilber Optics (DHO) have been performed on a set of aircrafts, whose models rendered first as binary images, and then as grayscale. It has been performed a very detailed analysis of requirements on resources of information system’s which would in a real world support the discriminatory decision of objects’ class for which the sample database has been creat…