Selenium Speciation in Rice Samples by Magnetic Ionic Liquid-Based Up-and-Down-Shaker-Assisted Dispersive Liquid-Liquid Microextraction Coupled to Graphite Furnace Atomic Absorption Spectrometry

A critical review of selected preconcentration techniques used for selenium determination in analytical samples

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.

Ionic Liquid-Assisted DLLME and SPME for the Determination of Contaminants in Food Samples

Developing effective and green methods for food analysis and separation has become an urgent issue regarding the ever-increasing concern of food quality and safety. Ionic liquids (ILs) are a new chemical medium and soft functional material developed under the framework of green chemistry and possess many unique properties, such as low melting points, low-to-negligible vapor pressures, excellent solubility, structural designability and high thermal stability. Combining ILs with extraction techniques not only takes advantage of ILs but also overcomes the disadvantages of traditional extraction methods. This subject has attracted intensive research efforts recently. Here, we present a brief review of the current research status and latest developments regarding the application of IL-assisted microextraction, including dispersive liquid–liquid microextraction (DLLME) and solid-phase microextraction (SPME), in food analysis and separation. The practical applications of ILs in determining toxic and harmful substances in food specimens with quite different natures are summarized and discussed. The critical function of ILs and the advantages of IL-based microextraction techniques over conventional extraction techniques are discussed in detail. Additionally, the recovery of ILs using different approaches is also presented to comply with green analytical chemistry requirements.

Magnetic Ionic Liquids in Sample Preparation: Recent Advances and Future Trends

In the last decades, a myriad of materials has been synthesized and utilized for the development of sample preparation procedures. The use of their magnetic analogues has gained significant attention and many procedures have been developed using magnetic materials. In this context, the benefits of a new class of magnetic ionic liquids (MILs), as non-conventional solvents, have been reaped in sample preparation procedures. MILs combine the advantageous properties of ionic liquids along with the magnetic properties, creating an unsurpassed combination. Owing to their unique nature and inherent benefits, the number of published reports on sample preparation with MILs is increasing. This fact, along with the many different types of extraction procedures that are developed, suggests that this is a promising field of research. Advances in the field are achieved both by developing new MILs with better properties (showing either stronger response to external magnetic fields or tunable extractive properties) and by developing and/or combining methods, resulting in advanced ones. In this advancing field of research, a good understanding of the existing literature is needed. This review aims to provide a literature update on the current trends of MILs in different modes of sample preparation, along with the current limitations and the prospects of the field. The use of MILs in dispersive liquid–liquid microextraction, single drop microextraction, matrix solid-phase dispersion, etc., is discussed herein among others.

Alcohol-DES based vortex assisted homogenous liquid-liquid microextraction approach for the determination of total selenium in food samples by hydride generation AAS: Insights from theoretical and experimental studies

This research article proposes a simple, quick, green and cheap approach for the determination of total selenium in food samples using alcohol-DES based vortex-assisted homogenous liquid-liquid microextraction (alcohol-DES-VA-HLLME) combination with hydride generation atomic absorption spectrometry (HG AAS). Analyte, complexing agent and working pH were Se(IV), Sudan-II and pH 4.0, respectively. In order to analyze the nature of the chemical interaction between Se(IV) ion and Sudan-II ligand, experimental results were supported with computational chemistry tools calculating quantum chemical descriptors like frontier orbital energies, hardness, softness, electronegativity, electrophilicity, nucleophilicity, transferred electron from the ligand to ion, electron donating power, electron accepting power, complexation energy, molecule-ion interaction energy. In addition, the alcohol-DES-VA-HLLME method was earned a good detection limit of 3.5 ng L^-1 and a wide calibration curve in the concentration range of 12-300 ng L^-1 (r: 0.9981). The validity of the method was evaluated by analyzing the two standard reference material (SRMs). The recoveries and relative standard deviations for 25 and 100 ng L^-1 of Se(IV) (N:5) were in the range of 1.2-2.5% and 92.1-103.7% respectively, which proved acceptable. The analytical results showed that the proposed method had important features such as cheapness, green, quick extraction and reuse, which made it attractive for the determination and efficient extraction of total selenium in the food samples.

Speciation Analysis of Trace Arsenic, Mercury, Selenium and Antimony in Environmental and Biological Samples Based on Hyphenated Techniques

In order to obtain a well understanding of the toxicity and ecological effects of trace elements in the environment, it is necessary to determine not only the total amount, but also their existing species. Speciation analysis has become increasingly important in making risk assessments of toxic elements since the toxicity and bioavailability strongly depend on their chemical forms. Effective separation of different species in combination with highly sensitive detectors to quantify these particular species is indispensable to meet this requirement. In this paper, we present the recent progresses on the speciation analysis of trace arsenic, mercury, selenium and antimony in environmental and biological samples with an emphasis on the separation and detection techniques, especially the recent applications of high performance liquid chromatography (HPLC) hyphenated to atomic spectrometry or mass spectrometry.