Phenolic content and antioxidant capacity of five Yellow European plums (Prunus domestica) were studied using heat reflux extraction. Fresh plums were extracted at 50°C and 70°C, while freeze dried plums were extracted at 50°C, 60°C, and 70°C. Quantification of phenolic compounds such as ascorbic acid, neochlorogenic acid, and chlorogenic acid, was performed using high performance liquid chromatography. Antioxidant activity was determined by evaluating the scavenging ability of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric (Fe 3+ ) free radicals. Total phenolic content and ferric reducing antioxidant potential were highest for freeze dried samples extracted at 60°C whereas extraction at 70°C resulted in the lowest yield. Neochlorogenic acid was the predominant phenolic compound in each plum genotype followed by ascorbic acid and chlorogenic acid. This study demonstrates that there is an adequate amount of health promoting phytochemicals within European plums, hence extraction of these compounds have potential for use towards functional food, nutraceutical, and pharmaceutical industries.

Yellow European Plums (YEPs) are a rich source of phenolic compounds and antioxidants, which can be obtained using microwave‐assisted extraction (MAE). During this study, two MAE experiments were performed to optimize MAE extraction parameters and the MAE process using YEPs. The first experiment was to determine the influence of independent variables such as solvent concentration (20, 60, and 100 %) and solid‐to‐solvent ratio (0.05, 0.1, and 0.15 g/mL), on the yield of total phenolic content (TPC) and antioxidant activity (1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP)), for ethanol and methanol, during MAE. Using a response surface methodology, the optimized extraction parameters for MAE were then found to be 60 % ethanol at a solid‐to‐solvent ratio of 0.1 g/mL. Using the optimized parameters from the first experiment, the second experiment evaluated the effect of microwave temperature (50, 60, 70 °C) and duration (5, 10, and 15 min) on TPC, DPPH, and FRAP, using a face‐centered central composite design. Individual phenolic compounds, including ascorbic acid, neochlorogenic acid, and chlorogenic acid, were quantified using high performance liquid chromatography. In the second experiment, it was observed that time and temperature had a significant (p ≤ 0.05) effect on the extraction of phenolic compounds from four genotypes of YEPs. However, due to their diverse phenolic composition, there was not one optimal operating time and temperature suitable for all genotypes.

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This study shows that salt type and pH affect the removal of perfluorooctanoic acid (PFOA) from water through flocculation and electro-enhanced flocculation. PFOA concentrations decreased by approximately 80% with 20 mM FeCl3 and initial pH = 3–10. Electro-enhanced flocculation at pH = 3 reduced PFOA concentrations in water by approximately 70% with CaCl2 and KCl, and by 50% with NaCl. At alkaline pH, PFOA removal was approximately 20% with CaCl2 and KCl. PFOA removal was negligible without salts or with AlCl3, and with NaCl at alkaline pH. Differences in PFOA removal are likely due to the settling behaviour of the cation-PFOA complexes formed.

An optimization study of sensitivity was performed in the determination of azide by reversed-phase ion-interaction HPLC. Sensitivity was optimized as a function of ioninteraction reagent concentration, ion-interaction reagent chain length, and mobile phase flow rate. Different series of experiments were performed in which each new series was planned on the basis of the results of the previous one. The model included square and cubic terms and second-order interactions. An ordinary least-squares (OLS) method was used as the regression method, and the all-model search was applied. The Fisher F test and R1 2 values were used to estimate the regression model quality. The model proposed contains five parameters and explains 98.21% of the variation in the data about the mean sensitivity. Chromatography under the improved experimental conditions predicted by the model gave a detection limit for sodium azide of 6.0 ppb.