A simple and rapid HPLC method for determination of chlorogenic acid (5-O-caffeoylquinic acid) in mate tea extracts was developed and validated. The chromatography used isocratic elution with a mobile phase of aqueous 1.5% acetic acid-methanol (85:15, v/v). The flow rate was 0.8 mL/min and detection by UV at 325 nm. The method showed good selectivity, accuracy, repeatability and robustness, with detection limit of 0.26 mg/L and recovery of 97.76%. The developed method was applied for the determination of chlorogenic acid in mate tea extracts obtained by ethanol extraction and liquid carbon dioxide extraction with ethanol as co-solvent. Different ethanol concentrations were used (40, 50 and 60%, v/v) and liquid CO₂ extraction was performed at different pressures (50 and 100 bar) and constant temperature (27 ± 1 °C). Significant influence of extraction methods, conditions and solvent polarity on chlorogenic acid content, antioxidant activity and total phenolic and flavonoid content of mate tea extracts was established. The most efficient extraction solvent was liquid CO₂ with aqueous ethanol (40%) as co-solvent using an extraction pressure of 100 bar.

Background/Aim. Tea and coffee are one of the most widely consumed beverages in the world due to their beneficial health effects which are largely associated with their phenolic compounds composition, including chlorogenic acid. The main aim of this study was to determine 5-caffeoylquinic acid (5-CQA), as one of the major classes of chlorogenic acid, in various commercial tea and coffee samples present at the Serbian market. Methods. A high-performance liquid chromatography (HPLC) method for determination of 5-CQA in plant extracts was applied to determine the content of this active compound in commercial tea and coffee samples. Mobile phase was aqueous 1.5% acetic acid - methanol (80:20, v/v) with the flow rate of 0.8 mL/min. Run time was 15 min and column temperature 25?C. The detection was performed at 240 nm. Results. The HPLC method was modified and revalidated. The 5-CQA content varied depending on the type of tea (white, green, black tea and mate) and the processing technology. Green tea had the highest 5-CQA content (16 mg/100 mL) among the analyzed tea samples. The content of 5-CQA in coffee samples ranged 0-36.20 mg/g of coffee and 0-46.98 mg/100 mL of beverage, showing that the content varied depending on the type of coffee, coffee processing technology and the formulation. Conclusion. The modified and revalidated HPLC method showed a good accuracy, repeatability, selectivity and robustness. The highest amount of 5-CQA was determined in green tea in comparison to white, black and mate tea because the increased oxidation level decreases the amount of 5-CQA. The obtained results for commercial coffee samples indicated that the formulation was the most important factor determining the amount of 5-CQA. It can be concluded that plant material selection, processing conditions and formulation have great influence on the amount of chlorogenic acid (5-CQA) in the final tea and coffee products.

The emission of untreated or insufficiently treated wastewater is very common in developing countries and consequently has harmful effects on the environment. The aim of this study was to analyse 24 physico-chemical parameters in raw wastewater and effluent after tertiary treatment (denitrification and disinfection) derived from meat-processing plants in Serbia during four sampling campaigns conducted for one year. The biochemical oxygen demand (BOD₅) and chemical oxygen demand (COD) were measured at high concentrations up to 6,960 and 14,160 mg/L, respectively, indicating a large amount of uncollected blood, solubilized fat, urine and faeces in discharged wastewater. Required limits of emission in all samples according to the European and national legislation for most of the studied parameters were exceeded. According to the obtained results, there is an imperative need for pretreatment of wastewater from meat industry before discharging it into the sewer. The applied wastewater treatment improved the quality of water by reducing BOD₅ and COD values to 97.97 and 98.08%, respectively, while phosphorus removal efficiency varied from 15.29 to 68.48%.