Deep Eutectic Solvent-Based Coating Sorbent for Preconcentration of Formaldehyde by Thin-Film Solid-Phase Microextraction Technique

Deep eutectic solvents with solid supports used in microextraction processes applied for endocrine-disrupting chemicals

The determination of endocrine-disrupting chemicals (EDCs) has become one of the biggest challenges in Analytical Chemistry. Due to the low concentration of these compounds in different kinds of samples, it becomes necessary to employ efficient sample preparation methods and sensitive measurement techniques to achieve low limits of detection. This issue becomes even more struggling when the principles of the Green Analytical Chemistry are added to the equation, since finding an efficient sample preparation method with low damaging properties for health and environment may become laborious. Recently, deep eutectic solvents (DESs) have been proposed as the most promising green kind of solvents, but also with excellent analytical properties due to the possibility of custom preparation with different components to modify their polarity, viscosity or aromaticity among others. However, conventional extraction techniques using DESs as extraction solvents may not be enough to overcome challenges in analysing trace levels of EDCs. In this sense, combination of DESs with solid supports could be seen as a potential solution to this issue allowing, in different ways, to determine lower concentrations of EDCs. In that aim, the main purpose of this review is the study of the different strategies with solid supports used along with DESs to perform the determination of EDCs, comparing their advantages and drawbacks against conventional DES-based extraction methods.

Hybrid materials based on deep eutectic solvents for the preconcentration of formaldehyde by SPME in coffee beverages

Coffee is one of the most widely consumed beverages. It can be prepared from green or roasted beans or from instant coffee. Unfortunately, in addition to the aroma obtained in the coffee roasting process, among others, formaldehyde can be produced. In this study, thin-film solid-phase microextraction was used to preconcentrate trace amounts of formaldehyde in different types of coffee with different roasting levels. For this purpose, 18 hybrid materials based on deep eutectic solvents were synthesized and tested as sorbents in thin-film solid-phase microextraction. The coffee samples were brewed, and then formaldehyde present in them was derivatized using the Nash reagent. The sample preparation procedure was optimized for selected DES-based sorbent using a central composite design method and validated. Formaldehyde was determined in almost all samples of second-crack coffee (roasted at 240 °C) at 0.17-0.75 ng mL-1 and in darker-colored instant coffees at 0.18-0.54 ng mL-1.

Fluorimetric determination of aqueous formaldehyde employing heating and ultrasound-assisted approach through its derivatization with a ß-diketone-nickel(2+) complex immobilized in a PMMA flow cell

Formaldehyde (FA) is a highly toxic substance present in many matrices, including freshwater as well as found in natural mechanisms such as rainfall and combustion of organic matter. Consumption of water contaminated with high levels of FA can cause severe short-term or long-term health problems. Due to these health risks, procedures are necessary to determine and quantify FA in aqua sources This paper reports on a study of fluorimetric determination of FA using a nickel(2 + )-diketonate coordination compound immobilized as a solid precursor. The compound was characterized by electronic absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry (TG), optical microscopy (OM), and scanner electron microscopy (SEM). The methodology was based on the reaction of the synthesized compound with an ammoniacal buffer generating a selective reagent for formaldehyde: fluoral-P. The product of the reaction generates 3,5-diacetyl-1,4-dihydrolutidine (DDL), which is responsible for the fluorescence of the system. Several parameters such as temperature, duration of heating time, and dilution effect with the best effects were studied to carry out FA determination. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg/L FA (R = 0.997 and n = 10), and a detection (3σ criterion) and quantification (10 σ criterion) limit estimated at 0.129 and 0.389 mg/L, respectively were achieved. The FA analysis was able to be conducted in 05 min with a relative standard deviation estimated at 1.10 %.

Applications of deep eutectic solvents in microextraction and chromatographic separation techniques: Latest developments, challenges, and prospects

Deep eutectic solvents (DESs) have recently sparked considerable attention in a variety of scientific and technological fields. The unique properties of DESs include biodegradability, easy preparation, low cost, and tuneability, rendering them a new and prospective alternative to hazardous solvents. Analytical chemistry is one of the most appealing fields where DESs proved to be applicable in either sample preparation or chromatographic separation. This review summarizes the new horizons dedicated to the application of DESs in microextraction and chromatographic separation. The utilization of DESs in microextraction, in chromatography as mobile phase additives, and in chromatographic material preparation processes is outlined. The enhancements in chromatographic performance achieved using DESs and any potential explanations deduced from the experimental findings were primarily discussed. An additional brief discussion on DESs preparation, characterization, and properties is addressed in this work. Finally, current challenges and future trends are also presented, supplying evidence for distinct possibilities regarding new research approaches involving DESs. This review can represent a guide and stimulate further research in this field.