In-tube solid-phase microextraction: Current trends and future perspectives.

In-tube solid-phase microextraction (IT-SPME) was developed about 24 years ago as an effective sample preparation technique using an open tubular capillary column as an extraction device. IT-SPME is useful for micro-concentration, automated sample cleanup, and rapid online analysis, and can be used to determine the analytes in complex matrices simple sample processing methods such as direct sample injection or filtration. IT-SPME is usually performed in combination with high-performance liquid chromatography using an online column switching technology, in which the entire process from sample preparation to separation to data analysis is automated using the autosampler. Furthermore, IT-SPME minimizes the use of harmful organic solvents and is simple and labor-saving, making it a sustainable and environmentally friendly green analytical technique. Various operating systems and new sorbent materials have been developed to improve its extraction efficiency by, for example, enhancing its sorption capacity and selectivity. In addition, IT-SPME methods have been widely applied in environmental analysis, food analysis and bioanalysis. This review describes the present state of IT-SPME technology and summarizes its current trends and future perspectives, including method development and strategies to improve extraction efficiency.

Evolution and current advances in sorbent-based microextraction configurations.

This review overviews the main developments achieved in analytical sample preparation regarding the use of solid sorbents as extractants in different sorbent-based miniaturized, micro-scale and microextraction methods. Two main groups are proposed for the classification of the current approaches, based on their operational mode: micro-solid-phase extraction (µ-SPE) and solid-phase microextraction (SPME), while describing their respective main sub-modes: static- and dispersive-µ-SPE, and SPME with fibers and in tube SPME. Furthermore, other important sorbent-based microscale approaches (e.g., stir bar sorptive extraction, stir cake sorptive extraction, stir bar sorptive-dispersive microextraction, and thin film microextraction, among others) are also considered.

Bioanalytical HPLC Applications of In-Tube Solid Phase Microextraction: A Two-Decade Overview.

In-tube solid phase microextraction is a cutting-edge sample treatment technique offering significant advantages in terms of miniaturization, green character, automation, and preconcentration prior to analysis. During the past years, there has been a considerable increase in the reported publications, as well as in the research groups focusing their activities on this technique. In the present review article, HPLC bioanalytical applications of in-tube SPME are discussed, covering a wide time frame of twenty years of research reports. Instrumental aspects towards the coupling of in-tube SPME and HPLC are also discussed, and detailed information on materials/coatings and applications in biological samples are provided.

An overview of the Brazilian contributions to Green Analytical Chemistry.

Green Analytical Chemistry (GAC) is a research field that seeks for more sustainable analytical approaches to minimize the toxicity and amounts of wastes without hindering the analytical performance. This is a trend in Analytical Chemistry worldwide and because of the diversity of innovations on this subject, Brazil stands out as the third in the list of the main contributors to GAC, with ca. 11.2% of the published articles. Significant innovations and interesting applications in several fields have been presented and Brazil is continuously moving from Chemistry to Green Chemistry also in the Analytical Chemistry field. Selected contributions for sample preparation, spectro- and electroanalysis, separation techniques, chemometrics, and also procedures for point-of-care measurements are critically reviewed.

In Vivo Sampling: A Promising Technique for Detecting and Profiling Endogenous Substances in Living Systems.

Endogenous substances, naturally occurring in living organisms, are critical components with physiological and biological functions. Discovery and quantitative measurement of endogenous substances in living biotas are important for food analysis, crop cultivation, and quality assessment. Low or non-invasive in vivo sampling techniques offer the advantages of minimal perturbation to the investigated system and potentially obtain more accurate feedback compared to in vitro sampling. In this perspective, we summarize the up-to-date progress in the development of microdialysis and solid-phase microextraction as valuable tools for in vivo sampling of endogenous substances in food and agriculture chemistry. We discuss their feasibility for on-site and real-time in vivo monitoring and highlight the prospects in searching for highly specific coatings, miniaturized sampling devices, and instruments that well meet the trend for high-efficient and high-throughput analyses.

Extraction media used in needle trap devices-Progress in development and application.

Analysis of trace compounds in complex matrices requires a preliminary step of sample preparation. From among widely used methodologies, microextraction techniques have become increasingly important as they tend towards being environmentally friendly. The needle trap (NT) extraction is a relatively new and promising technique which combines sampling, sample preparation and sample introduction. The core of the needle trap device is a suitable sorbent material packed inside the needle, that determines selectivity and efficiency of the method. In recent years, the effort towards improvement of needle trap extraction performance has led to development of new extraction media with higher selectivity and better adsorption properties, which may facilitate preconcentration of the target analytes. In this work, we present a review on the trends in development of sorbent materials used in the needle trap device including fibrous media, commercially available materials as well as sorbents prepared for special applications. This review also describes recent developments in the needle trap devices such as needle geometries, sorbent packing procedure and sampling methodologies. Comparison of needle trap extraction and solid phase microextraction (SPME) is presented to demonstrate the robustness of the former.

SPME as a promising tool in translational medicine and drug discovery: From bench to bedside.

Solid phase microextraction (SPME) is a technology where a small amount of an extracting phase dispersed on a solid support is exposed to the sample for a well-defined period of time. The open-bed geometry and biocompatibility of the materials used for manufacturing of the devices makes it very convenient tool for direct extraction from complex biological matrices. The flexibility of the formats permits tailoring the method according the needs of the particular application. Number of studies concerning monitoring of drugs and their metabolites, analysis of metabolome of volatile as well as non-volatile compounds, determination of ligand-protein binding, permeability and compound toxicity was already reported. All these applications were performed in different matrices including biological fluids and tissues, cell cultures, and in living animals. The low invasiveness of in vivo SPME, ability of using very small sample volumes and analysis of cell cultures permits to address the rule of 3R, which is currently acknowledged ethical standard in R&D labs. In the current review systematic evaluation of the applicability of SPME to studies required to be conduct at different stages of drug discovery and development and translational medicine is presented. The advantages and challenges are discussed based on the examples directly showing given experimental design or on the studies, which could be translated to the models routinely used in drug development process.

New trends in beer flavour compound analysis.

As the beer market is steadily expanding, it is important for the brewing industry to offer consumers a product with the best organoleptic characteristics, flavour being one of the key characteristics of beer. New trends in instrumental methods of beer flavour analysis are described. In addition to successfully applied methods in beer analysis such as chromatography, spectroscopy, nuclear magnetic resonance, mass spectrometry or electronic nose and tongue techniques, among others, sample extraction and preparation such as derivatization or microextraction methods are also reviewed.

Recent developments in stir bar sorptive extraction.

As a crucial step in qualitative and quantitative analysis, sample pretreatment is commonly used to isolate the target analytes, concentrate them, or convert them into the forms tailored to the instrumental analysis. In recent years, there has been a trend for sample pretreatment techniques to become more miniaturized and more environmentally friendly. Stir bar sorptive extraction (SBSE), which was developed in 1999, is such an environmentally friendly microextraction technique. Compared with other microextraction techniques, including solid phase microextraction and liquid phase microextraction, SBSE provides a higher extraction efficiency and better reproducibility owing to the much greater amount of the extraction phase, and no special skills are required. However, there are some problems associated with SBSE, such as the limited applicable coatings, coating abrasion of the laboratory-made stir bar, and the difficulty in automation, which restrict the further improvement and application of SBSE. This review focuses on the development of SBSE in the past decade, in terms of coating preparation, automated systems, novel extraction modes, its use with various instruments, and applications in food, environmental, and biological samples.

Developments and trends of molecularly imprinted solid-phase microextraction.

This review focuses on a solid-phase microextraction (SPME) method coupled with molecularly imprinted polymers (MIPs), namely molecularly imprinted solid-phase microextraction (MISPME). The first two sections discuss the summaries of conventional SPME and MIPs. The third section reviews the development of MISPME in past years, including the preparation of MISPME, and the applications to compounds in real samples.

Microextraction techniques in the analysis of food flavor compounds: A review.

Food flavor compounds due to the complexity of food as a matrix, and usually their very low concentrations in a product, as well as their low odor thresholds, create a challenge in their extraction, separation and quantitation. Food flavor volatiles represent compounds of different polarity, volatility and chemical character, which determine method of extraction for their isolation from food. Microextraction techniques, mainly SPME and SBSE have been used for food flavor compounds analysis for two decades. Microextraction methods other than SPME and SBSE are seldom used despite their analytical potential. The review discusses the nature of food flavor compounds, and different approaches to food flavor analysis. It summarizes the use of microextraction methods in food flavor compounds analysis based on papers published in the last 5years, and discusses the potential of microextraction methods in this field.

Current developments and future trends in solid-phase microextraction techniques for pharmaceutical and biomedical analyses.

Sample preparation is important for the isolation and concentration of desired trace components from complex matrices. Sample preparation is the most labor-intensive and error-prone process in analytical methodology, and greatly influences the reliable and accurate determination of analytes. The integration of sample preparation with various analytical instruments is most conveniently achieved by using microextraction techniques and/or microdevices. Solid-phase microextraction (SPME) is both simple and effective, enabling miniaturization, automation and high-throughput performance. Moreover, SPME has reduced analysis times, as well as the costs of solvents and disposal. This review describes current developments and future trends in novel SPME techniques, including fiber SPME, in-tube SPME and related new microextraction techniques. Especially innovative SPME approaches, including multi-well high-throughput sampling, ligand-receptor binding study for pharmacokinetics, direct in vivo sampling, chip-based microfluidic system, and new sampling techniques using intelligent carbon nanotube and temperature-response polymer in pharmaceutical and biomedical analysis are focused items.

Recent advances in SPME techniques in biomedical analysis.

Biomedical analyses of drugs, metabolites, poisons, environmental and occupational pollutants, disease biomarkers and endogenous substances in body fluids and tissues are important in the development of new drugs, therapeutic monitoring, forensic toxicology, patient diagnosis, and biomonitoring of human exposure to hazardous chemicals. In these analyses, sample preparation is essential for isolation of desired components from complex biological matrices and greatly influences their reliable and accurate determination. Solid-phase microextraction (SPME) is an effective sample preparation technique that has enabled miniaturization, automation and high-throughput performance. The use of SPME has reduced assay times, as well as the costs of solvents and disposal. This review focuses on recent advances in novel SPME techniques, including fiber SPME and in-tube SPME, in biomedical analysis. We also summarize the applications of these techniques to pharmacotherapeutic, forensic, and diagnostic studies, and to determinations of environmental and occupational exposure.

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.

Recent developments and applications of microextraction techniques in drug analysis.

Sample preparation is important for isolating desired components from complex matrices and greatly influences their reliable and accurate analysis. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, online coupling with analytical instruments, and low-cost operation through extremely low or no solvent consumption. Microextraction techniques, such as liquid-phase microextraction and solid-phase microextraction, have these advantages over the traditional approaches of liquid-liquid extraction and conventional solid-phase extraction. This review focuses primarily on these microextraction techniques developed over the last decade, and presents a summary of the characteristics of various approaches in drug analysis.

Solid-phase microextraction in bioanalysis: New devices and directions.

The primary objective of this review is to discuss recent technological developments in the field of solid-phase microextraction that have enhanced the utility of this sample preparation technique in the field of bioanalysis. These developments include introduction of various new biocompatible coating phases suitable for bioanalysis, such as commercial prototype in vivo SPME devices, as well as the development of sampling interfaces that extend the use of this methodology to small animals such as mice. These new devices permit application of in vivo SPME to a variety of analyses, including pharmacokinetics, bioaccumulation and metabolomics studies, with good temporal and spatial resolution. New calibration approaches have also been introduced to facilitate in vivo studies and provide fast and quantitative results without the need to achieve equilibrium. In combination with the drastic improvement in the analytical sensitivity of modern liquid chromatography-tandem mass spectrometry instrumentation, full potential of in vivo SPME as a sample preparation tool in life sciences can finally be explored. From the instrumentation perspective, SPME was successfully automated in 96-well format for the first time. This opens up new opportunities for high-throughput applications (>1000 samples/day) such as for the determination of unbound and total drug concentrations in complex matrices such as whole blood with no need for sample pretreatment, studies of distribution of drugs in various compartments and/or determination of plasma protein binding and other ligand-receptor binding studies, and this review will summarize the progress in this research area to date.

Trends in solventless sample preparation techniques for environmental analysis.

The paper presents recent trends in solventless sample preparation techniques for environmental analysis. First, a general classification of solventless methods is given. Next, three of them, treated as preferable techniques, i.e. SPME, SDME and HS, are presented in detail, with respect to their usability and effectiveness for environmental samples. Examples of all discussed techniques are given in the tables.

Developments in multiple headspace extraction.

This paper reviews new developments in multiple headspace extraction (MHE), especially its combination with two miniaturized extraction techniques, solid-phase microextraction (SPME) and single-drop microextraction (SDME). The combination of the techniques broadens the applicability of SPME and SDME to quantitative determination of analytes in complex liquid and solid matrixes. These new methods offer several advantages over traditional liquid-solid, liquid-liquid and headspace extraction techniques. The potential applications include extraction of volatiles and semivolatiles from environmental and physiological samples and from different polymer products such as medical and biomedical materials, food packaging and building materials. The theoretical principals of the techniques are also briefly reviewed.

Analytical microextraction: current status and future trends.

Analytical microextractions, defined as nonexhaustive sample preparation with a very small volume of extracting phase (microliter range or smaller) relative to the sample volume, represent an important development in the field of analytical chemistry. Analytes are extracted by a small volume of a solid or semi-solid polymeric material, as in solid-phase microextraction (SPME), or alternatively by a small volume of a liquid, as in liquid-phase microextraction (LPME). This paper gives an overview of the SPME and LPME techniques and discusses future trends. This includes a discussion of the different extraction formats available, commercial equipment, method transfer from traditional sample preparation methods to microextraction, and performance as well as robustness for the latter type of systems. In addition, the paper contains a unified approach to the understanding of extraction thermodynamics and kinetics applicable to both SPME and LPME.