Determination Of Phenolic Antioxidants Research Articles

Determination of phenolic antioxidants in tuna fillets canned in hydrosols with HPLC‐DAD

SummaryCanned tuna was fortified with a mixture of brine and hydrosols of aromatic plants (i.e. oregano, laurel, sage and lemon balm). An HPLC‐DAD method was developed and validated for the simultaneous determination of thirteen antioxidants in tuna fillets, including phenolic acids (gallic acid, vanillic acid, syringic acid and rosmarinic acid), flavonoids (catechin, epicatechin, vanillin, myricetin, rutin, quercetin, luteolin and apigenin) and one hydroxybenzaldehyde (syringaldehyde). The analytes showed satisfying recovery efficiency (82.1–92.1%), and the method presented excellent linearity (r2 > 0.99). The precision limit was ≤5.6% RSDr for intra‐day and ≤7.2% RSDR for inter‐day experiments. The determined analytes ranged between 8.86 mg (quercetin) and 512 mg (rosmarinic acid) per 100g tuna flesh (n = 10), verifying that the hydrosols fortified the tuna fillets.

乳製品中のフェノール系酸化防止剤の定量：AOAC法（ヘキサン─アセトニトリル分配法）と改良法（冷凍法）による比較

乳製品中のフェノール系酸化防止剤の定量：AOAC法（ヘキサン─アセトニトリル分配法）と改良法（冷凍法）による比較

Determination of Phenolic Antioxidants in Amazonian Medicinal Plants by HPLC with Pulsed Amperometric Detection

A wide range of chromatographic methods for the analysis of phenolic compounds in medicinal plants has been published over the years. However, no chromatographic methods with pulsed amperometric detection using a gold electrode have been described to analyze phenolic acids and flavonoids. Moreover, there is a lack of information regarding a modified mobile phase with β-cyclodextrin to determine these compounds in plants by RP-HPLC. For this reason, the present study developed and validated an HPLC–PAD method to determine 12 phenolic compounds in medicinal plants from Amazonia. The isocratic mobile phase was constituted by sodium phosphate 50 m mol L−1, methanol 30% (v/v), and β-cyclodextrin 1 m mol L−1 at pH 2.0. The method demonstrated low detection and quantification limits and robustness. The accuracy ranged from 82–114% for chlorogenic acid and rutin, respectively. Six species of medicinal plants from Amazonia used for medicinal and nutritional purposes were characterized and showed the presence of at least one of the phenolic compounds in the study.

Determination of phenolic antioxidants by micellar electrokinetic capillary chromatography with electrochemical detection

A new and efficient method for the determination of synthetic phenolic antioxidants (SPAs) has been developed by using micellar electrokinetic capillary chromatography (MECC) with electrochemical detection. Under the optimum conditions, all analytes were successfully separated within 13 min at the separation voltage of 18 kV in a 20 mmol/L borate running buffer (pH 7.4) containing 25 mmol/L sodium dodecyl sulfate. The excellent linearity was obtained in the concentration range from 5.0 × 10 −4 to 2.0 × 10 −6 mol/L and the detection limits ( S/ N = 3) of propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) range from 2.9 × 10 −7 to 2.7 × 10 −6 mol/L. This method has been proved to be effective and successfully applied for the determination of SPA in food products, providing a promising and convenient entry to monitor the superscale use of phenolic antioxidants.

Determination of Phenolic Antioxidants in Spilled Aviation Fuels by Gas Chromatography-Mass Spectrometry

A gas chromatography-mass spectrometric assay method was developed for the simultaneous determination of 2,6-di-tert-butylphenol (DTBP) and 2,4-dimethyl-6-tert-butylphenol (DMTBP) in aviation fuel. Extraction and purification were achieved with a solid phase extraction procedure using silica gel. Elution was performed with 30 mL of methylene chloride: pentane (2:3) following washing with 10 mL of n-pentane. The extract was concentrated to about 100 μL and analyzed by GC-MS (SIM). The peaks had good chromatographic properties by using a semi-polar column (Innowax) and the extraction of these compounds from samples gave recoveries of about 87% for DTBP and about 75% for DMTBP with small variations. Method detection limits were 5.0 ng mL−1 for DBMP and 7.0 ng mL−1 for DMTBP. The method may be useful for spilled fuel type differentiation between kerosene and JP-8.

Separation and Determination of Phenolic Antioxidants by HPLC with Surfactant/n-Propanol Mobile Phases

The influence of cationic and anionic surfactants and short-chain alcohols in the mobile phase on the retention of five antioxidants has been studied. The solutes chosen were butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and propyl, octyl, and dodecyl gallates (PG, OG, DG).The surfactants were hexadecyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), and n-propanol (PrOH) was the selected alcohol. A simple isocratic reversed-phase method for the antioxidant determination is proposed. Separation of five primary antioxidants takes 18 min with the mobile phase SDS 0.10 M/H 3 PO 4 0.01 M/PrOH 30%. Variation of the percentage of alcohol in the mobile phase permits optimization of the retention times of the antioxidants. Detection limits in the pg range were obtained for the all solutes. The method was used to determine the antioxidants in olive oil at three different levels, giving mean recoveries close to 100% for all the solutes (BHA 102%, PG 99%, OG 99%, DG 99%) except BHT (84%).

Separation and Determination of Phenolic Antioxidants by HPLC with Surfactant/n-Propanol Mobile Phases

Separation and Determination of Phenolic Antioxidants by HPLC with Surfactant/n-Propanol Mobile Phases

Determination of phenolic antioxidants in aviation jet fuel

The world-wide aviation jet fuel used for civil and military aircraft is of a kerosene type. To avoid peroxide production after the refinery process a specific antioxidant additive should be added on fuel. The antioxidants generally used are based on hindered phenols in a range of concentration 10–20 μg/ml. In the present work a specific method to measure the concentration of phenolic antioxidants is shown. The method is based on a liquid chromatographic technique with electrochemical detection. The technique, because of its selectivity, does not require sample pre-treatments. The analysis of a 5–10 ml fuel sample can be performed in less than 10 min with a sensitivity of 0.1 μg/ml and a RSD=2.5%. A comparison with another highly selective gas chromatographic technique with mass spectrometric detection with selected ion monitoring (GC–MS-SIM) is reported. The sensitivity of GC–MS-SIM method was 2 μg/ml with a RSD=3.1%.

Determination of Phenolic Antioxidants by HPLC with Amperometric Detection at a Nickel Phthalocyanine Polymer Modified Electrode

The suitability of nickel phthalocyanine polymer-coated glassy carbon electrodes for the amperometric detection of the phenolic antioxidants tert-butylhydroxytoluene (BHT), tert-butylhydroxyanisole (BHA), propyl gallate (PG) and tert-butylhydroquinone (TBHQ), after their separation by HPLC under gradient elution conditions, is demonstrated. An applied potential of +0.70 V (vs. Ag/AgCl) was used, which offers the best signal-to-noise ratio and is considerably lower than those reported in the literature with conventional electrodes. A good separation of the four antioxidants was obtained in 17 min. Furthermore, no fouling of the electrode surface was observed when using the polymer modified electrode during the whole working day. Using TBHQ as internal standard, detection limits of 5.5 ng, 7.5 ng and 30 ng (for a 50-μL volume injected) were obtained for BHA, PG and BHT, respectively. As an application, the determination of the antioxidants contained in commercial chewing gum samples was carried out by applying a simple extraction procedure. It was demonstrated that only BHT was present as antioxidant in the samples, in a concentration of 51±3 μg g–1. Sample linearity and recovery studies, after adding a known amount of BHT to the analyzed samples, confirmed the sutability of the proposed method.

Determination of Phenolic Antioxidants by HPLC with Amperometric Detection at a Nickel Phthalocyanine Polymer Modified Electrode

Determination of Phenolic Antioxidants by HPLC with Amperometric Detection at a Nickel Phthalocyanine Polymer Modified Electrode

Determination of Phenolic Antioxidants by Capillary Electrophoresis with Ultraviolet Detection

The use of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) for the separation of phenolic antioxidants is investigated. The aim of the work is to develop, through laboratory tests, a reliable method for the routine separation of gallic acid, six derivatives of gallic acid, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT). Phenolic substances, such as gallates, are widely used as food-grade antioxidants to prevent or delay oxidative deterioration. When adequate separation was not obtained in preliminary studies with CZE, the MEKC method was chosen for further development. A phosphate buffer containing sodium dodecyl sulfate (SDS) is used for the MEKC separations of the phenolic analytes. All the compounds could be separated within 15 min. The migration time of the compounds depends on the structure of the compounds and increases as follows: gallic acid amide (GAA), methyl gallate (MG), n-propyl gallate (PG), gallic acid trimethyl ether (GATE), gallic acid (GA), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), n-octyl gallate (OG), and n-dodecyl gallate (DG). The repeatability of the separation is tested by using two carboxylic acids as marker compounds in the determination of the electrophoretic mobilities of the analytes. The results show that the standard deviations for the migration indices are less than 1%, which means that the technique can also be used for rapid purity testing of real samples extracted from plant material.

Determination of phenolic antioxidants in polyethylene with dissolution by n‐heptane in an autoclave

AbstractA new procedure for quantitative analysis of phenolic antioxidants in polyolefins was tested. Thereby polyethylene samples were dissolved in pure n‐heptane or in n‐heptane/isopropanol mixture (1 000/5, v/v) in an autoclave at 160–170°C under elevated pressure. After precipitation of the polymer by cooling to room temperature, the obtained solution was either directly analysed by means of HPLC equipped with an UV‐detector, or the supernatant solvent used for the extraction was evaporated in vacuum at room temperature and the residue redissolved in acetonitrile. The concentration of antioxidants in the solution was determined by isocratic HPLC. The advantage of this procedure is the short time of about 2 h needed for analysis and the good reproducibility of results (σ = 3–5%).

Determination of phenolic antioxidants in pharmaceutical formulations by liquid chromatography and migration study on HDPE packagings

The performance of UV diode-array, spectrometric and electrochemical detectors was compared in the chromatographic analysis of trace amounts of six phenolic antioxidants. Quantitative validation was undertaken; the linearity range was wider using UV detection although the limits of detection were lower with electrochemical detection. UV detection was applied both to identification of an antioxidant in a hydrophilic suspension and to a migration study.

Determination of phenolic antioxidants in JP-5 jet fuels by gas chromatography-mass selective detection

Determination of phenolic antioxidants in JP-5 jet fuels by gas chromatography-mass selective detection

Determination of Phenolic Anti-Oxidants in Edible Oil by High-Performance Liquid Chromatography with Amperometric Detector

Abstract A high-performance liquid chromatography (HPLC) with amperometric detection was investigated for the analysis of 2-and 3-tert-butyl-4-hydroxyanisole (BHA), 3,5-di-tert−butyl-4-hydroxytoluene (BHT), and tert−butyl-hydroquinone (TBHQ) in edible oil. The reversed-phase system developed was combined with an amperometric detector, the working electrode of which was made of glassy carbon, in order to compare the sensitivity and selectivity of ultraviolet and fluorometric detection. For the amperometric detection of HPLC, cyclic voltammetry was used to monitor the electrochemical properties of the phenolic antioxidants. A simple isolation procedure, based on the continuous liquid-liquid partition technique, was examined for the extraction and clean up of the antioxidants from edible oil. The recovery rates of BHA, BHT, and TBHQ added salad oil were between 90.2-107.7% in the range of 1-50 ppm of the antioxidants. By the present method, BHA, BHT, and TBHQ were well separated, identified and quantitated w...

Determination of phenolic antioxidants in polypropylene by derivative ultraviolet spectroscopy

A method has been developed for the determination of two phenolic antioxidants exhibiting virtually identical ultraviolet absorption spectra (2,6-di-tert-butyl-4-methylphenol and 4-substituted 2,6-xylenol, denoted by AO-4K and Chemantox AO-49, respectively). The absorption coefficient of AO-4K is an order of magnitude higher than that of Chemantox AO-49. The anti-oxidants can be distinguished in alkaline medium, where the latter forms phenolate readily, thus allowing the utilisation of the bathochromic shift for its determination. The use of derivative spectroscopy reduces light scattering and matrix interferences when extracts from polypropylene samples are measured.

The determination of phenolic anti-oxidants in edible oils and fats by high-performance liquid chromatography

A simple procedure for the extraction of phenolic anti-oxidants with methanol is described. The extracted compounds are determined by gradient elution with retention times of 4.0–13.2 min; an internal standard technique is used for quantification.

Determination of Phenolic Antioxidants in Dehydrated Mashed Potatoes

Determination of Phenolic Antioxidants in Dehydrated Mashed Potatoes

Selective fluorescence quenching and determination of phenolic antioxidants

Selective fluorescence quenching and determination of phenolic antioxidants