Immunoaffinity Extraction and Alternative Approaches for the Analysis of Toxins in Environmental, Food or Biological Matrices.

The evolution of instrumentation in terms of separation and detection allowed a real improvement of the sensitivity and analysis time. However, the analysis of ultra-traces of toxins in complex samples requires often a step of purification and even preconcentration before their chromatographic analysis. Therefore, immunoaffinity sorbents based on specific antibodies thus providing a molecular recognition mechanism appear as powerful tools for the selective extraction of a target molecule and its structural analogs to obtain more reliable and sensitive quantitative analysis in environmental, food or biological matrices. This review focuses on immunosorbents that have proven their efficiency in selectively extracting various types of toxins of various sizes (from small mycotoxins to large proteins) and physicochemical properties. Immunosorbents are now commercially available, and their use has been validated for numerous applications. The wide variety of samples to be analyzed, as well as extraction conditions and their impact on extraction yields, is discussed. In addition, their potential for purification and thus suppression of matrix effects, responsible for quantification problems especially in mass spectrometry, is presented. Due to their similar properties, molecularly imprinted polymers and aptamer-based sorbents that appear to be an interesting alternative to antibodies are also briefly addressed by comparing their potential with that of immunosorbents.

Recent Developments of Stir Bar Sorptive Extraction for Food Applications: Extension to Polar Solutes.

Stir bar sorptive extraction (SBSE) is a miniaturized and solvent-less sample preparation method for extraction and concentration of organic compounds from aqueous samples. The method is based on sorptive extraction, whereby the solutes are extracted into a polymer, such as polydimethylsiloxane (PDMS), coated on a stir bar. Using an apolar PDMS coating, SBSE provides high recoveries for apolar solutes; however, SBSE recoveries for polar solutes are low. Although several more polar coatings for SBSE were developed, these extraction phases are mostly not compatible with thermal desorption (TD) and/or have inferior performance characteristics related to robustness, bleeding, stability, etc. compared to PDMS. In this perspective, two recently introduced SBSE approaches are described that can be used to extend the applicability of a PDMS coating to more polar solutes: (1) SBSE with freeze concentration [ice concentration linked with extractive stirrer (ICECLES)], which is based on the concentration of analytes by gradually reducing the phase ratio (sample/extraction phase), and (2) SBSE using a solvent-swollen PDMS [solvent-assisted SBSE (SA-SBSE)], which is based on a combination of polarity modification and volume increase by PDMS phase swelling using certain types of solvents while maintaining the original characteristics of the PDMS phase.

Recent advances in analytical methods for the determination of 4-alkylphenols and bisphenol A in solid environmental matrices: A critical review.

The problem of endocrine disrupting compounds (EDCs) in the environment has become a worldwide concern in recent decades. Besides their toxicological effects at low concentrations and their widespread use in industrial and household applications, these pollutants pose a risk for non-target organisms and also for public safety. Analytical methods to determine these compounds at trace levels in different matrices are urgently needed. This review critically discusses trends in analytical methods for well-known EDCs like alkylphenols and bisphenol A in solid environmental matrices, including sediment and aquatic biological samples (from 2006 to 2018). Information about extraction, clean-up and determination is covered in detail, including analytical quality parameters (QA/QC). Conventional and novel analytical techniques are compared, with their advantages and drawbacks. Ultrasound assisted extraction followed by solid phase extraction clean-up is the most widely used procedure for sediment and aquatic biological samples, although softer extraction conditions have been employed for the latter. The use of liquid chromatography followed by tandem mass spectrometry has greatly increased in the last five years. The majority of these methods have been employed for the analysis of river sediments and bivalve molluscs because of their usefulness in aquatic ecosystem (bio)monitoring programs. Green, simple, fast analytical methods are now needed to determine these compounds in complex matrices.

Development of a multi-residue method for the determination of human and veterinary pharmaceuticals and some of their metabolites in aqueous environmental matrices by SPE-UHPLC-MS/MS.

The aim of the present work was to develop and validate a multi-residue method for the analysis of 33 human and veterinary pharmaceuticals (non-steroidal anti-inflammatory drugs (NSAIDs)/analgesics, antibiotics and psychiatric drugs), including some of their metabolites, in several aqueous environmental matrices: drinking water, surface water and wastewaters. The method is based on solid phase extraction (SPE) followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and it was validated for different aqueous matrices, namely bottled water, tap water, seawater, river water and wastewaters, showing recoveries between 50% and 112% for the majority of the target analytes. The developed analytical methodology allowed method detection limits in the low nanograms per liter level. Method intra- and inter-day precision was under 8% and 11%, respectively, expressed as relative standard deviation. The developed method was applied to the analysis of drinking water (bottled and tap water), surface waters (seawater and river water) and wastewaters (wastewater treatment plant (WWTP) influent and effluent). Due to the selectivity and sensitivity of the optimized method, it was possible to detect pharmaceuticals in all the aqueous environmental matrices considered, including in bottled water at concentrations up to 31ngL-1 (salicylic acid). In general, non-steroidal anti-inflammatory drugs/analgesics was the therapeutic group most frequently detected, with the highest concentrations found in wastewaters (acetaminophen and the metabolite carboxyibuprofen at levels up to 615 and 120µgL-1, respectively).

Recent progress for the selective pharmaceutical analyses using molecularly imprinted adsorbents and their related techniques: A review.

A well-organized molecularly imprinted polymer (MIP) provides the amazing selective molecular recognition ability, which have been close to natural enzymes and antibodies. One of the most efficient applications of MIPs is a selective separation and detection of pharmaceutical compounds in biological and/or environmental samples. MIP-based solid phase extraction now capacitates the selective concentration of the targeting compound from real samples. Also, many of the attractive methodological approaches and applications regarding the analysis of pharmaceutical samples using molecular imprinting technologies (MITs) have been reported in recent years. In this review, we summarize a part of the recent these works related to a new preparation concept of the adsorption adsorbents, sensitive sensor techniques, cell/bacteria separation, and drug delivery system. We believe that our concise summary will be of assistance to additional methodological MITs and highly selective separations/detections.

Recent advances in SPE-chiral-HPLC methods for enantiomeric separation of chiral drugs in biological samples.

In medical practices, the determination of enantiomeric ratio of the chiral drugs is very important for their activities, bioavailabilities and biodegradation. Only homochiral medication is safe for humans. The chiral analysis in biological samples is the first and most important step. The present article describes the technical strategies of the enantiomeric resolution of racemic drugs in biological samples. Attempts have been made to describe sample preparation by solid-phase extraction and enantiomeric resolution by chiral high-performance liquid chromatography. Various chiral stationary phases used in chiral separations of racemic drugs have been described. Efforts are also made to discuss the chiral recognition mechanism and future perspectives of chiral analyses in biological samples.

The pivotal role of mass spectrometry in determining the presence of chemical contaminants in food raw materials.

During recent years, a rising interest from consumers and various governmental organizations towards the quality of food has continuously been observed. Human intervention across the different stages of the food supply chain can lead to the presence of several types of chemical contaminants in food-based products. On a normal daily consumption basis, some of these chemicals are not harmful; however, for those that present a risk to consumers, legislation rules were established to specify tolerance levels or in some cases the total forbiddance of these specific contaminants. Hence, the use of appropriate analytical tools is recommended to properly identify chemical contaminants. In that context, mass spectrometry (MS)-based techniques coupled or not to chromatography offer a vast panel of features such as sensitivity, selectivity, quantification at trace levels, and/or structural elucidation. Because of the complexity of food-based matrices, sample preparation is a crucial step before final detection. In the present manuscript, we review the contribution and the potentialities of MS-based techniques to ensure the absence of chemical contaminants in food-based products.

Molecularly imprinted polymers for sample preparation: a review.

In spite of the huge development of analytical instrumentation during last two decades, sample preparation is still nowadays considered the bottleneck of the whole analytical process. In this regard, efforts have been conducted towards the improvement of the selectivity during extraction and/or subsequent clean-up of sample extracts. Molecularly imprinted polymers (MIPs) are stable polymers with molecular recognition abilities, provided by the presence of a template during their synthesis and thus are excellent materials to provide selectivity to sample preparation. In the present review, the use of MIPs in solid-phase extraction and solid-phase microextraction as well as its recent incorporation to other extraction techniques such as matrix-solid phase dispersion and stir bar sorptive extraction, among others, is described. The advantages and drawbacks of each methodology as well as the future expected trends are discussed.

Sorbent preconcentration procedures coupled to capillary electrophoresis for environmental and biological applications.

Sorbent preconcentration offers good strategies to overcome the poor detection limits of capillary electrophoresis (CE). The present review focuses on the recent trends of the coupling between sorbent preconcentration techniques, namely solid-phase extraction (SPE) and solid-phase microextraction (SPME), to capillary electrophoresis (CE). Special attention is given to their environmental and biological application. We also discuss the most important advantages and disadvantages of the different methodologies and briefly outline the new trends of the coupling between sorbent preconcentration and CE.

Current trends in solid-phase-based extraction techniques for the determination of pesticides in food and environment.

Solid-phase extraction (SPE) procedures for pesticide residues in food and environment are reviewed and discussed. The use of these procedures, which include several approaches such as: matrix solid-phase dispersion (MSPD), solid-phase micro-extraction (SPME) and stir-bar sorptive extraction (SBSE), represents an opportunity to reduce analysis time, solvent consumption, and overall cost. SPE techniques differ from solvent extraction depending on the interactions between a sorbent and the pesticide. This interaction may be specific for a particular pesticide, as in the interaction with an immunosorbent, or non-specific, as in the way a number of different pesticides are adsorbed on apolar or polar materials. A variety of applications were classified according to the method applied: conventional SPE, SPME, hollow-fiber micro-extraction (HFME), MSPD and SBSE. Emphasis is placed on the multiresidue analysis of liquid and solid samples.