Polyphenols are natural compounds with enhanced antioxidant properties. They are present in relatively high concentrations in fruit/vegetable by-products. Therefore, there is a need for the development of efficient and cost-effective methods for the separation and purification of these valuable compounds. Traditional extraction with organic solvents needs to be switched to novel methods that are more efficient, with reduced extraction times and low consumption of organic solvents. Aiming at developing sustainable processes for the separation and purification of phenolic compounds, we used three model compounds, namely resveratrol, quercetin, and gallic acid, to investigate ionic liquid-based aqueous biphasic systems (IL-ABSs) formed by cholinium-based IL in combination with polypropylene glycol with a molecular mass of 400 g/mol (PPG400). The ABS composition in the two-phase region was selected according to a previously determined phase diagram. Extraction studies indicated the preferential partition of resveratrol and quercetin toward the hydrophobic PPG-rich phase that is mainly dominated by its hydrophobic nature and the strong salting-out effect of ILs. On the other hand, due to its considerably hydrophilic nature, gallic acid preferentially migrates toward the IL phase. The achieved results from grape stem extract demonstrated high extraction efficiencies of cholinium dihydrogen phosphate (~99% for resveratrol for the PPG phase and 78% for gallic acid for the IL phase), with considerable selectivity, demonstrating promising outcomes for potential applications.

Sage has been used in traditional medicine to prevent and treat many health problems. This study aimed to determine and compare the phytochemical composition and antioxidative activity of sage leaf extracts obtained with 50% methanol (50MSE) and 80% methanol (80MSE). We determined the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) in extracts. Terpenoids were identified using gas chromatography-mass spectrometry (GC–MS), and the radical scavenging capacity of extracts was measured using DPPH assay. TPC was higher in 80MSE, TTC was higher in 50MSE, and TFC did not differ. GC–MS analysis showed that the content of α-thujone and L-camphor was low in both extracts, with higher content in 50MSE. DPPH assay indicated that a slightly lower IC50 value and higher antioxidant potential had 80MSE. Results pointed out that the polarity of the solvent and water content had different effects on the extraction of polyphenols and terpenoids.

This study investigates tetrabutylphosphonium-based ionic liquids for food dye removal via extraction using aqueous biphasic systems with ammonium sulfate. Furthermore, these ionic liquids were used for activated carbon regeneration and employed for dye removal from the water as well. This dual approach achieved high extraction efficiencies (≈ 90%) and nearly complete regeneration (98%) of the activated carbon used as a food dye adsorbent. These findings underscore the potential of tetrabutylphosphonium ionic liquids for managing dye-contaminated water.

The safety of drinking water is crucial for public health. Industrial and human activities have increased the use of heavy metals (cobalt, nickel, manganese) in water sources. These non-biodegradable, potentially carcinogenic metals pose serious health risks in drinking water. This study developed an efficient aqueous biphasic system (ABS) for removing these metals using real drinking water samples. Two ionic liquids, tetrabutylphosphonium DTPA ([TBP][DTPA]) and tetrabutylphosphonium acetate ([TBP][Ac]), were selected as ABS components, with ammonium sulfate as the salting-out agent. Phase diagrams were established, and extraction efficiencies were evaluated. The [TBP][DTPA] IL demonstrated superior performance, achieving over 95% extraction efficiency for all metals due to the stable complex formation with metal ions. The ABS proved highly effective for real samples, making it a promising approach for ensuring safe drinking water.

More environment-friendly solvents in analytical chemistry are almost inevitable in both sample preparation and analysis to meet the high standards of sustainable chemistry and human welfare. In this review paper, a critical look at the advantages and still unsolved problems of most potential classes of green solvents is presented to give an overview of the current state-of-the-art in this field. Replacing volatile organic compounds (VOCs) by ecofriendly and benign solvents in extractions/separations in sample preparation, as the most tedious and demanding step in analysis, is one of roads toward sustainable chemistry. Water under sub- and supercritical conditions, carbon-dioxide, ionic liquids (ILs), deep eutectic solvents (DESs), and those of natural origin (NADES) belong to the most promising classes of solvents in green analytical chemistry. Basic theory and mechanisms of their use illustrated by representative but not exhaustive list of examples related to complex matrices (environmental and natural food products) from analytical practice are presented in this review. Perspectives of QuEChERS, in line with GAC principles, are highlighted, in line with current trends of "going green" for quick, easy, cheap, effective, rugged, and safe analytical methods. Compliance with green chemistry (GC), especially green analytical chemistry (GAC) principles, is not a fashionable issue but, more the trend toward a sustainable future with greener chemistry; thus, green metrics are an unavoidable tool to measure how green the applied method or procedure is. Herein, the most common tools will be presented and discussed, such as national environmental method index (NEMI), analytical ecoscale, green analytical procedure index (GAPI), analytical greenness calculator (AGREE), complementary green analytical procedure index (ComplexGAPI), and analytical greenness metric for sample preparation (AGREEprep). The future trends for research and development in this still expanding field are presented in a critical view of advantages and disadvantages as well as improvement of the validation of analytical procedures. The creation of new certified reference materials (CRMs) and validated methods for specified analytes in complex matrices is a demanding task in the coming years. Tailor-made solvents with physicochemical properties for intended use are required for the selective extraction and separation and open numerous possibilities and huge potential for future research and industrial applications.