Search results for "Flame Ionization"
showing 10 items of 29 documents
Sterols in infant formulas: validation of a gas chromatographic method.
2017
AbstractSterols are components present in the fat fraction of infant formulas (IFs). Their characterization is therefore of interest, though there are no official reference methods for their analysis in these matrices.Aim: To validate a gas chromatographic method with flame ionization detection for the determination of animal (cholesterol and desmosterol) and plant sterols (brassicasterol, campesterol, stigmasterol, β-sitosterol and sitostanol) found in IFs.All correlation coefficients obtained for the calibration curves of sterols studied were >0.99. Limits of detection (<1 μg/100 mL) and quantification (<4 μg/100 mL) are suitable for sterols determination in IFs. The within-assay precisio…
Bioactive triterpenes of protium heptaphyllum gum resin extract display cholesterol-lowering potential
2021
Hypercholesterolemia is one of the major causes of cardiovascular disease, the risk of which is further increased if other forms of dyslipidemia occur. Current therapeutic strategies include changes in lifestyle coupled with drug administration. Statins represent the most common therapeutic approach, but they may be insufficient due to the onset of resistance mechanisms and side effects. Consequently, patients with mild hypercholesterolemia prefer the use of food supplements since these are perceived to be safer. Here, we investigate the phytochemical profile and cholesterol-lowering potential of Protium heptaphyllum gum resin extract (PHE). Chemical characterization via HPLC-APCI-HRMS2 and…
Chemical characterization of a variety of cold-pressed gourmet oils available on the Brazilian market
2018
Different specialty extra virgin oils, produced by cold-pressing fruits/nuts (olive, pequi, palm, avocado, coconut, macadamia and Brazil nut) and seeds (grapeseed and canola), and retailed in the Brazilian region of Minas Gerais, were chemically characterized. Specifically, for each type of oil, the fatty acid composition was elucidated by GC-FID, the contents of selected polyphenols and squalene were determined respectively by UHPLC-MS and UHPLC-PDA, whereas minerals were explored by means of ICP-MS. Olive oil was confirmed to have the highest MUFA content due to a valuable level of oleic acid, while oils from grapeseed, Brazil nut and canola were marked by nutritionally important PUFA lev…
Risk assessment of benzene in food samples of Iran's market
2018
Abstract The concentration of benzene in ninety-eight collected food and drink samples (carbonated beverage, fruit juice, pickle, lime juice, mayonnaise and salad dressing, 16 samples from each) from Iran local markets were investigated using gas chromatography equipped with flame ionization detector (GC-FID). Moreover, the correlation of benzene concentration with sodium benzoate and ascorbic acid concentrations was assessed. Benzene concentration in carbonated beverages, fruit juices, pickle, lime juices, mayonnaise and salad dressing were 3.57 ± 1.70, 5.17 ± 3.63, 4.37 ± 2.24, 4.99 ± 0.54, 1.38 ± 0.87 and 1.47 ± 0.83 μg/L, respectively, being in all cases below the acceptable limit (10 μ…
Determination of alcohols in essential oils by liquid chromatography with ultraviolet detection after chromogenic derivatization
2013
Abstract An HPLC-UV method to determine compounds having a hydroxyl functional group in plant essential oils is developed. The sample is diluted with 1,4-dioxane and the analytes are derivatized with phthalic anhydride. The derivatives (phthalates hemiesters) are separated on a C8 column using an acetonitrile (ACN)/water gradient. Separation conditions were optimized using the DryLab® method development software. For the alcohols and phenols present in mint and rose essential oils, optimization led to a ca. 40 min gradient time and a column temperature of 8 °C. The alcohol and its derivatives were identified using HPLC with mass spectrometry (MS) detection. A large sensitivity enhancement w…
Quantification of poisons for Ziegler Natta catalysts and effects on the production of polypropylene by gas chromatographic with simultaneous detecti…
2020
[EN] This article describes a new simultaneous method for the analysis of sulfur-type poisons, hydrocarbons and permanent gases affecting the productivity of the Ziegler Natta catalyst during the synthesis of polypropylene on an industrial scale in a fluidized-bed reactor. The identification was achieved employing a configuration of the seven-valve chromatographic system, with events at different times, allowing distribution of the sample through multiple columns, and finally reaching the helium ionization detectors of pulsed discharge, flame ionization and mass spectrometry. The results obtained show a good precision of the method used because the variability was less than 1.02% in area an…
Stability of Plant Sterols in Ingredients Used in Functional Foods
2011
The content of plant sterol (PS) and their oxidation products (POPs) in eight ingredients used to enrich functional foods was studied. A gas chromatographic (GC) technique with mass-spectrometric detection was used for identification, while GC with a flame ionization detector (GC-FID) was used for quantification. β-Sitosterol was the most abundant phytosterol, and the main POPs found were derived from this compound (7α/β-hydroxysitosterol, 7-ketositosterol, and sitostanetriol). The total amount of POPs found in the ingredients ranged from 29.03 to 110.02 μg/100 g PS. The β-sitosterol oxidation rates ranged from 10 to 50 μg β-sitosterol oxides/100 g of β-sitosterol. In view of this low rate …
Analysis of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization.
2006
International audience; Addition of long-chain polyunsaturated fatty acids (LC-PUFAs) from marine oil into food products implies preliminary refining procedures of the oil which thermal process affects the integrity of LC-PUFAs. Deodorization, the major step involving high temperatures, is a common process used for the refining of edible fats and oils. The present study evaluates the effect of deodorization temperature on the formation of LC-PUFA geometrical isomers. Chemically isomerized eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as reference samples. Fish oil samples have been deodorized at 180, 220 and 250 °C for 3 h and pure EPA and DHA fatty acid methyl esters…
High-resolution pyrolysis–gas chromatography with a movable reaction zone
1997
Abstract A new device was constructed for pyrolysis–gas chromatography and it was laboratory tested. The device enables the thermal degradation of polymers inside a capillary pre-column and transfer of the reaction zone into a column oven. The pyrolysis procedure described protects the thermally sensitive compounds prior to pyrolysis, prevents the process of irreversible condensation of high-boiling pyrolysis products during the chromatographic process and eliminates extracolumn effects on the peak broadening.
Lipid hydroperoxides determination in milk‐based infant formulae by gas chromatography
2003
A simple gas chromatograph using a flame ionization detector and a polar capillary column method is proposed for determining hydroperoxides in the lipid fraction of milkbased infant formulas. Tricosanoic acid is used as internal standard. The method includes the following steps: a) the extraction of fat with chloroform/methanol (2:1, v/v), b) the reduction of hydroperoxide acids to hydroxide acids with hydrogen gas and palladium as a catalyst, c) the transmethylation to obtain the methyl esters with acetyl chloride and methanol/ hexane (4:1, v/v), and d) an acetylation with acetic anhydride/ pyridine (4:1, v/v) to obtain an acetoxy derivate of the hydroxide present. Two chromatography runs,…