Search results for "liquid chromatography"

Influencia del procesado industrial sobre las características químico-físicas y contenido en lípidos y antioxidantes del salvado de arroz

2009

Se investigaron las características químico-físicas de los salvados de arroz en distintos momentos de su procesado industrial, incluyendo materia prima (salvados de arroz blanco y vaporizado), salvado peletizado y salvado desgrasado. Se determinó la humedad, la acidez y el índice de peróxidos. Utilizando extractos en éter de petróleo y cromatografía de gases, se estableció el contenido lipídico total y los perfiles de los ácidos grasos. Mediante HPLC se determinaron los tocoferoles y el γ-orizanol. El salvado de arroz vaporizado mostró la mayor concentración de lípidos y la menor acidez, lo que indica que el vaporizado es el proceso más eficaz para estabilizar el salvado. Los ácidos oleico,…

High-performance liquid chromatography of the mycotoxin sterigmatocystin and its application to the analysis of mouldy rice for sterigmatocystin.

1981

Automated multi-dimensional liquid chromatography

2004

A comprehensive on-line sample clean-up with an integrated two-dimensional HPLC system was developed for the analysis of natural peptides. Samples comprised of endogenous peptides with molecular weights up to 20 kDa were generated from human hemofiltrate (HF) obtained from patients with chronic renal failure. The (poly-)peptides were separated using novel silica-based restricted access materials with strong cation-exchange functionalities (SCX-RAM). The size-selective sample fractionation step is followed by cation-exchange chromatography as the first dimension. The subsequent second dimension of separation is based on hydrophobic interaction using four parallel short reversed-phase (RP) co…

On-fibre solid-phase microextraction coupled to conventional liquid chromatography versus in-tube solid-phase microextraction coupled to capillary li…

2006

This paper compares the advantages and disadvantages of two different configurations for the extraction of triazines from water samples: (1) on-fibre solid-phase microextraction (SPME) coupled to conventional liquid chromatography (LC); and (2) in-tube SPME coupled to capillary LC. In-tube SPME has been effected either with a packed column or with an open capillary column. A critical evaluation of the main parameters affecting the performance of each method has been carried out in order to select the most suitable approach according to the requirements of the analysis. In the on-fibre SPME configuration the fibre coating was polydimethylsiloxane (PDMS)-divinylbenzene (DVB). The limits of de…

Pyrolysis-GC-MS and CuO-oxidation-HPLC in the characterization of HMMs from sediments and surface waters downstream of a pulp mill

1998

Abstract High molecular mass fractions of lignin and humic compounds in sediments and waters downstream of a pulp mill were characterized applying pyrolysis-gas chromatography-mass spectrometry. The results were compared to those obtained using reversed phase HPLC on the cupric oxide oxidation products. The chromatographic data of both pyrolysis and cupric oxide oxidation were also subjected to the principal component analysis (PCA). The sediment samples and fractions obtained by ultrafiltration of river water samples were freeze dried prior to characterization. The sediment samples were also extracted using 2 M sodium hydroxide solution. The extracts were ultrafiltrated, freeze dried and c…

The impact of baking on chlorinated paraffins: Characterization of C10–C17 chlorinated paraffins in oven-baked pastry products and unprocessed pastry…

2019

Abstract This study presents an HPLC–ESI–Q–TOF method for simultaneous quantification of short-chain chlorinated paraffins (SCCPs, C10–13) and an additional characterization of medium-chain chlorinated paraffins (MCCPs, C14–17) in oven-baked pastry products (n = 38) and unprocessed pastry dough material (n = 15). Almost 2 times higher SCCP levels were found in the dough material. ΣSCCP concentrations in products ranged from 0.3 ng g−1 to 23.0 ng g−1 (mean: 6.3 ng g−1), while the results for dough ranged from 5.8 ng g−1 to 22.8 ng g−1 (mean: 12.9 ng g−1). Regardless of the sample matrix, the most abundant CP homologue groups were hepta- and octa-chlorinated undecanes and dodecanes. The avera…

Detection and quantification of patulin and griseofulvin by high pressure liquid chromatography in different strains of Penicillium griseofulvum Dier…

1988

Patulin and griseofulvin production by twelve strains ofPenicillium griseofulvum Dierckx, eleven of which were isolated from pistachio (Pistacia vera) nuts and the other was supplied by the Spanish Collection of Type Culture, was investigated. Six strains of the eleven isolated had ability to produce patulin and griseofulvin in Yes medium. All the strains studied had no ability to produce patulin in Wickerham medium. Griseofulvin production was significant in both media but higher in Wickerham.These metabolites were separated and determined in the chloroform extracts of cultures by high performance liquid chromatography with ultraviolet detection. The best conditions were: acetonitrile - wa…

Ceftazidime Determination in Serum by High-pressure Liquid Chromatography

2004

A rapid and sensitive high-pressure liquid chromatographic method with simple sample preparation was developed for the quantitative analysis of the beta-lactam antibiotic ceftazidime (CAS 78439-06-2, Fortum). A good linear relationship was established between the peak area and the amount of ceftazidime injected over a concentration range of 1 to 200 microg/ml. The detection limit of the method was calculated to be 0.9 microg/ml. Stability was shown at 4 degrees C and at -196 degrees C for time periods of 2 h and 84 days, respectively.

Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: Stat…

2013

Peak profiles in chromatography are characterised by their height, position, width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution, the plots are parabolic, although often, the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics, eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mas…

Comparison of monolithic and microparticulate columns for reversed-phase liquid chromatography of tryptic digests of industrial enzymes in cleaning p…

2011

Abstract Enzymes of several classes used in the formulations of cleaning products were characterized by trypsin digestion followed by HPLC with UV detection. A polymeric monolithic column (ProSwift) was used to optimize the separation of both the intact enzymes and their tryptic digests. This column was adequate for the quality control of raw industrial enzyme concentrates. Then, monolithic and microparticulate columns were compared for peptide analysis. Under optimized conditions, the analysis of tryptic digests of enzymes of different classes commonly used in the formulation of cleaning products was carried out. Number of peaks, peak capacity and global resolution were obtained in order t…