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Selenium (Se) is considered to be an essential trace element needed for all living organisms. The importance, deficiency, and toxic effects of Se mainly depend on its quantity and chemical nature. It has been observed that the inorganic versions of Se are more hazardous than the organic versions. This review is mainly focused on the application of different extraction methods used for Se extraction and determination such as microextraction, solid-phase extraction (SPE), and their modified modes in the last 12 years. The use of different dispersive medium (magnetic field, ultrasonic radiation, and vortex agitator) to enhance Se separation is also part of this review. The usage of environmentally friendly solvents such as supramolecular solvents, hydrophobic deep eutectic solvents (DESs), and ionic liquids (ILs) are also the focus of attention in this review. This review is also emphasized the application of advanced microextraction methods, particularly liquid-phase microextraction (LPME). The most recent advances in LPME extraction techniques for Se in various environmental samples, as well as their prospects, are reviewed. Additionally, a summary of cheap, simple, and accurate techniques that have not yet been used to determine small amounts of Se has been provided.

For the first time, air-assisted cloud point extraction (AA-CPE) procedure was applied to determine selenium in black tea samples at room temperature. The Air agitation is powered by a small fish tank generator to improve the dispersion phase and reduce the critical temperature for surfactants. The ligand and surfactant were 1-(2-hydroxy-5-ptolylazo-phenyl)-ethan-one (HPAPEO) and TritonX-100, respectively. Afterward, the extracted selenium complexes were injected into a hydride generation atomic absorption spectrometer (HGAAS). At the optimal conditions of experimentation, linearity from 0.3 to 1000 µg l-1 was constructed with an enhancement factor, preconcentration factor, detection limit, and extraction recovery of 150, 100, 0.02 µg l-1, and 99.1-102%, respectively. The AA-CPE technique's accuracy has been proven using certified reference materials. Ultimately, the Red-Green-Blue (RGB12), Analytical Greenness Metric Approach (AGREE), and Complementary Green Analytical Procedure Index (ComplexGAPI) scales have been applied to assess the whiteness and greenness of this method. An accurate evaluation of the criteria has been performed to ensure this procedure is eco-friendly for the environment. [ABSTRACT FROM AUTHOR]

A supramolecular solvent (SUPRAS) was prepared from undecanoic acid and tetrabutylammonium hydroxide and used as an extraction solvent. A fast microextraction approach based on air-assisted solidified floating organic drop (AA-SFODME) coupled to a hydride generation atomic absorption spectrometer (HG-AAS) for arsenic and selenium traces determination in water and food samples was developed. The air bubbles enhanced the extraction efficiency by reducing both the time and the required chemical amounts. The 2-((4-iodophenyl) diazenyl)-8-hydroxyquinoline (IPHQ) was used as a chelation reagent. The experimental factors that impact extraction efficiency were improved and optimized. The limits of detection (LODs) for arsenic and selenium were 0.09 and 0.07 µg L−1, respectively. Also, the preconcentration factors (PFs) and enhancement factors (EFs) were found to be 100 and 103 for both arsenic and selenium, respectively. The linearity of both two calibration curves ranged from 0.10 to 700 µg L−1, with linear regression coefficients (R2) of 0.9986 and 0.9978, respectively. Finally, the greenness score was determined using two tools: the analytical greenness calculator (AGREE) and the Blue Applicability Grade Index (BAGI). The high greenness scores from these tools can make this method even more environmentally friendly and practical. [Display omitted] • A new air-assisted solidified-floating organic drop microextraction-based supramolecular solvent was proposed. • Supramolecular solvent used as an extraction solvent. • A rapid and sensitive microextraction coupled to HG-AAS for arsenic and selenium detection. • Low detection limits and broad linear ranges have been found. • The greenness and applicability profiles were determined. [ABSTRACT FROM AUTHOR]