Optimization and Validation of RP-HPLC-UV/Vis Method for Determination Phenolic Compounds in Several Personal Care Products

Spectrofluorimetric determination of butylated hydroxytoluene and butylated hydroxyanisole in their combined formulation: application to butylated hydroxyanisole residual analysis in milk and butter

Butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are two antioxidants that have been extensively used in many applications. Both are well known for their debatable health risks due to their multiple intake sources. Therefore, conservative limits are set for them in different regulations adapted to the matrices in which they exist. Here we present a simple spectrofluorimetric method for the determination of BHT and BHA based on their native fluorescence and synchronous scanning mode. The type of solvent and the interval between emission and excitation wavelengths were carefully optimized. Under the optimized conditions, good linearities were obtained between the emission intensity and the corresponding concentrations of BHT and BHA over the range of 3-18 µg/mL and 0.1-7 µg/mL, respectively with a good correlation coefficient (r > 0.99). The limits of detection were 0.9 and 0.02 µg/mL, and the quantification limits were 3 and 0.05 µg/mL for BHT and BHA, respectively. The suggested procedure was validated according to ICH guidelines Q2 (R1). Furthermore, the method's greenness was assessed by three different methods, and it proved to be eco-reasonable. The method was successfully applied to the determination of BHT and BHA in pharmaceutical formulations. We also applied the suggested method for monitoring the residual BHA in conventional, powdered milk and butter, with good recovery in spiked samples.

Comparison of Identification and Quantification of Polyphenolic Compounds in Skins and Seeds of Four Grape Varieties

The aim of this study was to identify and quantify polyphenolic compounds in skin extracts from four Bulgarian grape varieties and compare them to those of seed extracts. The values of total phenolic contents, flavonoids, anthocyanins, procyanidins and an ascorbic acid in grape skin extracts were determined. The antioxidant capacities of skin extracts were evaluated using four different methods. The total phenolic content of skin extracts was 2-3 times lower than those of seed extracts. The significant difference between total parameter values of individual grape varieties were also found. According to the total phenolic content and antioxidant capacity of skin extracts, the different grape varieties were arranged in the following order: Marselan ≥ Pinot Noir ˃ Cabernet Sauvignon ˃ Tamyanka. The individual compounds in the grape skin extracts were determined using RP-HPLC and compared with those of the seed extracts. The determined composition of skin extracts was significantly different from the seed extracts' composition. Quantitative evaluation of the procyanidins and catechins in the skins was carried out. A correlation between phenolic contents, individual compounds and antioxidant capacity of different extracts was found. The studied grape extracts have a potential to be applied as natural antioxidants in the pharmaceutical and food industries.

Ultrasensitive Electrochemical Detection of Butylated Hydroxy Anisole via Metalloporphyrin Covalent Organic Frameworks Possessing Variable Catalytic Active Sites

Three novel two-dimensional metalloporphyrin COFs (MPor-COF-366, M = Fe, Mn, Cu) were fabricated by changing the metal atoms in the center of the porphyrin framework. The physicochemical characteristics of MPor-COF-366 (M = Fe, Mn, Cu) composites were fully analyzed by diverse electron microscopy and spectroscopy. Under optimal conditions, experiments on determining butylated hydroxy anisole (BHA) at FePor-COF-366/GCE were conducted using differential pulse voltammetry (DPV). It is noted that the FePor-COF-366/GCE sensor showed excellent electrocatalytic performance in the electrochemical detection of BHA, compared with MnPor-COF-366/GCE and CuPor-COF-366/GCE. A linear relationship was obtained for 0.04-1000 μM concentration of BHA, with a low detection limit of 0.015 μM. Additionally, the designed sensor was successfully employed to detect BHA in practical samples, expanding the development of COF-based composites in electrochemical applications.

Synergistic behavior of flammable dust mixtures: A novel classification

In this work the flammable/explosive behavior of mixtures of flammable dusts is investigated. In particular, minimum ignition temperature, minimum ignition energy, maximum pressure and deflagration index have been measured at varying the relative content of dusts in the mixtures. The thermal behavior of these mixtures has been also studied by means of DSC analysis coupled to chemical analysis performed by HPLC and ATR-FTIR. Depending on the mixtures, a synergistic behavior has been found due to physical and/or chemical reactions. For some mixtures, the more severe behavior has been attributed to the presence of a eutectic point (niacin/anthraquinone, ascorbic acid/niacin), in other cases, to chemical reactions with the formation of volatiles (ascorbic acid/irganox 1222, ascorbic acid/glucose). On this basis, we propose a new classification of dusts mixtures in three mixtures safety classes (MSC): MSC 0 (no synergistic effect, ideal behavior); MSC 1 (deviation from ideality, safety parameters included between those of the pure dusts) and MSC 2 (at least 1 parameter with more sever value than those of pure dusts).

Determination of synthetic phenolic antioxidants in soft drinks by stir-bar sorptive extraction coupled to gas chromatography-mass spectrometry

The synthetic phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were pre-concentrated by stir-bar sorptive extraction and thermally desorbed (SBSE-TD) before analysis by GC-MS. Several parameters affecting the derivatisation step and both SBSE extraction and thermal desorption were carefully optimised. When the analyses of BHA and TBHQ in their acetylated, silylated and underivatised forms were compared, the best results were obtained when the in-situ derivatisation procedure with acetic anhydride was employed. Quantification was carried out using carvacrol as the internal standard, providing quantification limits of between 0.11 and 0.15 ng ml(-1), depending on the compound. Recovery assays for samples spiked at two concentration levels, 1 and 5 ng ml(-1), provided recoveries in the 81-117% range. The proposed method was applied in the analysis canned soft drinks and the analytes were found in five of the 10 samples analysed.