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At least 55 records · Page 3Linked to original sources
PubMed2005

Identification of isomers and subsidiary colors in commercial Fast Green FCF (FD&C Green No. 3, Food Green No. 3) by liquid chromatography-mass spectrometry and comparison between amounts of the subsidiary colors by high-performance liquid chromatography and thin-layer chromatography-spectrophotometry.

The existence of five of the six expected isomers in commercial Fast Green FCF (G3: Food Green No. 3, FD&C Green No. 3, CAS No. 2353-45-9, C.I. No. 42053), the main product of which is m,m-G3 and the sub-products of which are presumed to be m,p-G3, o,m-G3, p,p-G3, o,p-G3 and o,o-G3, was confirmed using LC/MS, and the levels of the isomers, m,m-G3, m,p-G3, p,p-G3, o,m-G3 and o,p-G3, were determined by analytical HPLC. The existence of seven subsidiary colors that were decomposed from G3 was also confirmed using LC/MS. The levels of the subsidiary colors in ethanol extracts from TLC were determined by HPLC and spectrophotometry, and these results were compared. It was clear that the values determined by TLC-spectrophotometry were higher than those by HPLC. It was recommended that the levels of subsidiary colors in G3 should be determined by HPLC.

Chromatography, High Pressure Liquid↗
PubMed1996

On-line high-performance liquid chromatography-solvent evaporation-high-performance liquid chromatography-capillary gas chromatography-flame ionisation detection for the analysis of mineral oil polyaromatic hydrocarbons in fatty foods.

An automated on-line method is described that involves a first LC separation on a large column, evaporation of a 6-ml fraction in an on-line solvent evaporator, a second LC separation using a different mobile phase, fractionating the components of interest and transfer to GC through the in-line vaporizer/overflow interface. The method is designed for the injection of a large amount of food extract (e.g. up to 200 mg of fat) and is applied to the analysis of mineral oil material in a linseed oil.

Chromatography, Gas↗
PubMed1999

Comparative studies of the leachate of an industrial landfill by gas chromatography-mass spectrometry, liquid chromatography-nuclear magnetic resonance and liquid chromatography-mass spectrometry.

Nowadays, the need to have a realistic characterization of industrial effluents in the environment has become more and more recognized. A palette of different analytical methods both for sample extraction and instrumental analysis are available today, some older, others introduced more recently. The aim of this research is to compare a number of these techniques. To do this we studied a real leachate from an industrial landfill and carried out chemical analyses for organic pollutants, using different extraction methods based on solid-phase extraction and solid-phase microextraction and different instrumental techniques such as GC-MS, LC-MS, NMR and LC-NMR. Results show the performances of the different techniques, which are complementary.

Chromatography, Liquid↗
PubMed2006

Evaluation of radial chromatography versus axial chromatography, practical approach.

Developments in packing and packing port design of radial columns in recent years have resulted in a claimed significant increase in performance of this process chromatography technology. In this first study, the main chromatographic parameters as efficiency, capacity factor, asymmetry and resolution were evaluated in a unique one-to-one comparison between a 120 ml bed-volume and 6 cm bed length radial chromatography mini-process column against a 50 mm diameter, 6 cm bed height and 120 ml bed-volume axial chromatography column. Radial chromatography showed an increase in efficiency by 31% in the number of plates per meter while the equilibration could be reduced by 0.4-0.5 column volumes. The asymmetry factor for bovine serum albumin in radial chromatography showed a reduction of 20% while the reduction of the asymmetry factor of the smaller protein ovotransferrin decreased even by 46% in comparison to the performance of the comparative axial chromatography column. Therefore in radial chromatography resolution improved up to 20%. The retention volume was similar in both cases. For radial chromatography, the decrease in "width at half height" at Height Equivalent of Theoretical Plates (HETP) measurements was 40% while the decrease of the over-all width of the peak was 27%. For adsorbed/desorbed proteins, the elution peak showed similar results: "width at half height" decreased to 45% while the over-all width of the peak decreased by 28%. The concentration of the non-retained protein in the flow-through (lysozyme), increased by 35% while the concentration of the eluted fraction (serum albumin bovine), increased with 40% in the radial chromatography columns. The better results obtained with the radial column were probably the consequence of the geometrical design of this device (larger inlet surface area and small outlet surface area which concentrate the eluted fraction).

Chromatography, Liquid↗
PubMed2004

Automated multiresidue analysis of pesticides in olive oil by on-line reversed-phase liquid chromatography-gas chromatography using the through oven transfer adsorption-desorption interface.

A multiresidue, automated and rapid method for the determination of pesticide residues in olive oil is presented. The method employs the through oven transfer adsorption-desorption interface for the on-line coupling of reversed-phase liquid chromatography and gas chromatography. In this fully automated system, olive oil is directly injected with no sample pre-treatment step other than filtration. Methanol-water is used as eluent in the liquid chromatography pre-separation step. The selected liquid chromatography fraction containing the pesticides is automatically transferred to the gas chromatography. The liquid chromatography column flow during elution is different from the flow during the transfer. Using a flame ionisation detector, pesticide detection limits varied from 0.1 to 0.3 mg/l.

Adsorption↗
PubMedDate not supplied

Determination of trans octadecenoic acids by silver-ion chromatography-gas liquid chromatography: an intercomparison of methods.

Several silver-ion chromatography-gas liquid chromatography (GLC) techniques for the determination of trans octadecenoic acids in partially hydrogenated vegetable fats were collaboratively evaluated. Twelve laboratories participated in the study. All collaborators used high polarity fused silica capillary columns for the separation of fatty acid methyl esters by GLC; 7 collaborators isolated trans monoenes by silver-ion liquid chromatography (Ag-LC) and the remainder used silver-ion thin-layer chromatography (Ag-TLC). Eight artificially prepared materials [soybean oil spiked with either methyl elaidate, trielaidin, or trans octadecenoates isolated from partially hydrogenated sunflower oil (PHSO)] and 2 matrix materials (PHSO and a blend of PHSO and palm oil) served as test samples. Ag-TLC and Ag-LC proved to be equivalent techniques for the prefractionation of trans monoenes. Recovery of methyl elaidate, trielaidin, or trans octadecenoates isolated from PHSO varied between 97.9-103.7% over a concentration range of 1 to 30 g trans fatty acids/100 g. Reproducibility relative standard deviation (RSDR) for the spiked samples were in the range of 3.1-8.6% for 30-1% trans monoene content. For the 2 matrix samples (mean 3.75 and 19.08% trans monoene content) RSDR was 13.2 and 3.6%. The hyphenated techniques tested proved to be highly accurate and sufficiently precise methods for the determination of trans monoenes in partially hydrogenated vegetable fats. Procedural variations of the silver-ion chromatography prefractionation step (separation mode, mobile phase, and detection systems) did not significantly influence the results of the test. Therefore, silver-ion chromatography is a robust method, which does not need rigorous standardization to achieve high precision of test results. A further benefit of the hyphenated technique is that any type of efficient polar capillary column can be used.

Chromatography, Gas↗