Application of deep eutectic solvents in atomic absorption spectrometry

Deep eutectic solvents as a green alternative for trace element analysis in food and beverage samples: Recent advances and challenges

Metals and metalloids have different effects on human health even at trace levels. Some of them are essential for living organisms while others can be toxic. Therefore, the determination of trace elements in food and beverage is highly important to understand their impact in human health. A new generation of solvents named deep eutectic solvents (DES) has emerged as a green alternative for trace element analysis, owing to their low toxicity, biodegradability, and high extraction capacity. In recent years, the application of DES in extraction techniques for trace element analysis in food and beverage samples has increased significantly. This review summarizes recent advances and challenges on the application of DES to develop microextraction techniques useful for the analysis of samples with complex matrices. The importance of the use of biodegradable substances instead of classic organic solvents, which are toxic, volatile, and flammable in methods for elemental analysis with a positive environmental impact is also highlighted. Finally, conclusions and future challenges arising from the use of DES in microextraction techniques are discussed.

Toxicity, arsenic speciation and characteristics of hyphenated techniques used for arsenic determination in vegetables. A review

Arsenic (As) speciation is an interesting topic because it is well recognized that the toxicity of this metalloid ultimately depends on its chemical form. More than 300 arsenicals exist naturally. However, As can be present in four oxidation states: As-III, As0, AsIII and AsV. Long-term exposure to As from different sources, such as anthropogenic processes, or water, fauna and flora contaminated with As, has put human health at risk for decades. There are many side-effects correlated with exposure to InAs species, such as skin problems, respiratory diseases, kidney problems, cardiovascular diseases and even cancer. There are different levels and types of As in foods, particularly in vegetables. Furthermore, different chemical methods and techniques have been developed. Therefore, this review focuses on the general properties of various approaches used to identify As species in vegetation samples published worldwide. This includes various approaches (different solvents and techniques) used to extract As species from the matrix. Then, versatile chromatographic and non-chromatographic systems to separate different forms of As are reviewed. Finally, the general properties of the most common instruments used to detect As species from samples of interest are listed.

Tetrabutylammonium-chloride-glycerol of deep eutectic solvent functionalized MnO2: a novel mimic enzyme for the quantitative and qualitative colorimetric detection of L-cysteine

L-Cysteine is a common amino acid that plays an important role in human livelihood and production. Therefore, a novel method for the simultaneous quantitative and qualitative determination of L-cysteine by a colorimetric detection system is proposed. As a viable oxidase mimic, [N₄₄₄₄]Cl-G/MnO₂, which consisted of MnO₂ nanosheets functionalized by a tetrabutylammonium chloride-glycerol ([N₄₄₄₄]Cl-G) based deep eutectic solvent (DES) was fabricated. Owing to the oxidation of MnO₂ nanosheets, [N₄₄₄₄]Cl-G/MnO₂ could oxidize the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into a blue product (oxTMB) with the characteristic UV-vis spectrum absorbance at 652 nm. The oxidation of TMB by DES/MnO₂ was inhibited when L-cysteine was introduced, and the absorbance decreased proportionally with the increase in L-cysteine concentration. Due to this inhibition effect, a colorimetric detection system ([N₄₄₄₄]Cl-G/MnO₂-TMB) was developed for the quantitative determination of L-cysteine. Under optimal conditions, the assay showed good linearity over the concentration range of 0.125-2.00 μg mL^-1 with a low detection limit of 5.96 ng mL^-1. A study of the inhibition mechanism demonstrated that the sulfhydryl group of L-cysteine could decompose [N₄₄₄₄]Cl-G/MnO₂ into Mn²⁺, thus limiting the conversion of TMB to oxTMB. In addition, the [N₄₄₄₄]Cl-G/MnO₂-TMB system was used in test strips for the visual qualitative detection of L-cysteine. The selectivity and test strip results demonstrated the high selectivity, simple operation, and rapid response of the [N₄₄₄₄]Cl-G/MnO₂-TMB system for the qualitative detection of L-cysteine. Given the satisfying performance of the detection strategy, colorimetric sensing based on the [N₄₄₄₄]Cl-G/MnO₂-TMB system is considered to have prospective application value in the quantitative and qualitative detection of L-cysteine.