Microextraction by Packed Sorbent (MEPS) and Solid-Phase Microextraction (SPME) as Sample Preparation Procedures for the Metabolomic Profiling of Urine

Recent Advances in Bioanalysis of Cephalosporins Toward Green Sample Preparation

This review highlights recent advances in the bioanalysis of cephalosporins using liquid chromatographic methods, focusing on green sample preparation (GSP) techniques. Cephalosporins, a class of β-lactam antibiotics, are critical in combating bacterial infections but present challenges related to drug resistance and toxicity. This article evaluates various sample preparation methods, including solid-phase extraction, solid-phase microextraction, and protein precipitation, which have been employed in the extraction and quantification of cephalosporins from biological matrices. Special attention is given to the optimization of critical parameters, such as pH, extraction solvents, and purification techniques to maximize analytes' recovery and sensitivity. Emerging trends in GSP, such as the use of molecularly imprinted polymers and miniaturized processing devices, are also discussed. The review underscores the growing importance of integrating environmentally friendly approaches in cephalosporin bioanalysis, paving the way for future innovations in bioanalytical research.

Comparative study of sample preparation procedures to determine the main compounds in ayahuasca beverages by QuEChERS and high-performance liquid chromatography analysis

INTRODUCTION

Ayahuasca is a psychoactive drink originally consumed by indigenous people of the Amazon. The lack of regulation of this drink leads to uncontrolled consumption, and it is often consumed in religious contexts.

OBJECTIVE

The aim of this work is to compare three miniaturised extraction techniques for extracting the main ayahuasca compounds from beverages.

METHODOLOGY

Three sample pretreatment techniques were evaluated (dispersive liquid-liquid microextraction [DLLME], microextraction by packed sorbent [MEPS] and QuEChERS [Quick, Easy, Cheap, Effective, Rugged and Safe]) for the simultaneous extraction of N,N-dimethyltryptamine (DMT), tetrahydroharmine (THH), harmine, harmaline, harmol and harmalol from ayahuasca beverage samples. Then, the most promising technique (QuEChERS) was chosen to pre-concentrate the analytes, subsequently detected by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD).

RESULTS

The procedure was optimised, with the final conditions being 500 μL of extractor solvent, 85 mg of primary secondary amine (PSA) and 4 s of vortexing. The analytical method was validated, showing to be linear between 0.16 and 10 μg/mL for β-carbolines and between 0.016 and 1 μg/mL for DMT, with coefficients of determination (R2) between 0.9968 and 0.9993. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 0.16 μg/mL for all compounds, except for DMT (0.016 μg/mL) and extraction efficiencies varied between 60.2% and 88.0%.

CONCLUSION

The analytical methodology proved to be accurate and precise, with good linearity, LODs and LLOQs. This method has been fully validated and successfully applied to ayahuasca beverage samples.

Microextraction techniques for occupational biological monitoring: Basic principles, current applications and future perspectives

The application of green microextraction techniques (METs) is constantly being developed in different areas including pharmaceutical, forensic, food and environmental analysis. However, they are less used in biological monitoring of workers in occupational settings. Developing valid extraction methods and analytical techniques for the determination of occupational indicators plays a critical role in the management of workers' exposure to chemicals in workplaces. Microextraction techniques have become increasingly important because they are inexpensive, robust and environmentally friendly. This study aimed to provide a comprehensive review and interpret the applications of METs and novel sorbents and liquids in biological monitoring. Future perspectives and occupational indicators that METs have not yet been developed for are also discussed.

Applications of magnetic solid-phase extraction in the sample preparation of natural product analysis (2020-2023)

Sample preparation, including extraction, separation, and purification, is a vital process for natural product analysis. As an attractive sample pretreatment method, magnetic solid-phase extraction (MSPE) has gained plenty of attention, mainly due to its simpler operation, less consumption of organic solvents, and shorter processing time than traditional SPE. This updated review is devoted to summarizing the applications of MSPE based on different magnetic nanomaterials in the analysis of various natural products in complex matrixes, such as biological samples, plants, and Chinese herbal preparations in the past four years (2020-2023). The preparation and fabrication of different materials are briefly introduced. Furthermore, the extraction mechanism and interaction forces between adsorbent and analytes are elaborated, and the advantages and disadvantages of different adsorbents coupled with various analytical methods for MSPE of different natural products are summarized. Moreover, the future trends and opportunities for MSPE in the natural product analysis are discussed. It is expected that this work can provide updated information for future research on the applications of MSPE in such fields.

Targeted quantitative metabolic profiling of brain-derived cell cultures by semi-automated MEPS and LC-MS/MS

The accurate characterisation of metabolic profiles is an important prerequisite to determine the rate and the efficiency of the metabolic pathways taking place in the cells. Changes in the balance of metabolites involved in vital processes such as glycolysis, tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), as well as in the biochemical pathways related to amino acids, lipids, nucleotides, and their precursors reflect the physiological condition of the cells and may contribute to the development of various human diseases. The feasible and reliable measurement of a wide array of metabolites and biomarkers possesses great potential to elucidate physiological and pathological mechanisms, aid preclinical drug development and highlight potential therapeutic targets. An effective, straightforward, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was developed for the simultaneous quali-quantitative analysis of 41 compounds in both cell pellet and cell growth medium obtained from brain-derived cell cultures. Sample pretreatment miniaturisation was achieved thanks to the development and optimisation of an original extraction/purification approach based on digitally programmed microextraction by packed sorbent (eVol®-MEPS). MEPS allows satisfactory and reproducible clean-up and preconcentration of both low-volume homogenate cell pellet lysate and cell growth medium with advantages including, but not limited to, minimal sample handling and method sustainability in terms of sample, solvents, and energy consumption. The MEPS-LC-MS/MS method showed good sensitivity, selectivity, linearity, and precision. As a proof of concept, the developed method was successfully applied to the analysis of both cell pellet and cell growth medium obtained from a line of mouse immortalised oligodendrocyte precursor cells (OPCs; Oli-neu cell line), leading to the unambiguous determination of all the considered target analytes. This method is thus expected to be suitable for targeted, quantitative metabolic profiling in most brain cell models, thus allowing accurate investigations on the biochemical pathways that can be altered in central nervous system (CNS) neuropathologies, including e.g., mitochondrial respiration and glycolysis, or use of specific nutrients for growth and proliferation, or lipid, amino acid and nucleotide metabolism.

Automated microextraction by packed sorbent of endocrine disruptors in wastewater using a high-throughput robotic platform followed by liquid chromatography-tandem mass spectrometry

An automated microextraction by packed sorbent followed by liquid chromatography-tandem mass spectrometry (MEPS-LC-MS/MS) method was developed for the determination of four endocrine disruptors-parabens, benzophenones, and synthetic phenolic antioxidants-in wastewater samples. The method utilizes a lab-made repackable MEPS device and a multi-syringe robotic platform that provides flexibility to test small quantities (2 mg) of multiple extraction phases and enables high-throughput capabilities for efficient method development. The overall performance of the MEPS procedure, including the investigation of influencing variables and the optimization of operational parameters for the robotic platform, was comprehensively studied through univariate and multivariate experiments. Under optimized conditions, the target analytes were effectively extracted from a small sample volume of 1.5 mL, with competitive detectability and analytical confidence. The limits of detection ranged from 0.15 to 0.30 ng L-1, and the intra-day and inter-day relative standard deviations were between 3 and 21%. The method's applicability was successfully demonstrated by determining methylparaben, propylparaben, butylated hydroxyanisole, and oxybenzone in wastewater samples collected from the São Carlos (SP, Brazil) river. Overall, the developed method proved to be a fast, sensitive, reliable, and environmentally friendly analytical tool for water quality monitoring.

Automated and semi-automated packed sorbent solid phase (micro) extraction methods for extraction of organic and inorganic pollutants

In this study, the packed sorbent solid phase (micro) extraction methods from manual to automated modes are reviewed. The automatic methods have several remarkable advantages such as high sample throughput, reproducibility, sensitivity, and extraction efficiency. These methods include solid-phase extraction, pipette tip micro-solid phase extraction, microextraction by packed sorbent, in-tip solid phase microextraction, in-tube solid phase microextraction, lab-on-a-chip, and lab-on-a-valve. The recent application of these methods for the extraction of organic and inorganic compounds are discussed. Also, the combination of novel technologies (3D printing and robotic platforms) with the (semi)automated methods are investigated as the future trend.

Simultaneous microextraction of pesticides from wastewater using optimized μSPEed and μQuEChERS techniques for food contamination analysis

Food contamination with pesticides poses significant risks to consumer safety and undermines confidence in food supply chains. Detecting pesticides in food samples is a challenging task that requires efficient extraction techniques. This study aims to compare and validate two microextraction techniques, μSPEed and μQuEChERS-dSPE, for the simultaneous extraction of eight pesticides (paraquat, thiabendazole, asulam, picloram, ametryn, atrazine, linuron, and cymoxanil) from wastewater samples. A good analytical performance was obtained for both methodologies, with selectivity, linearity in the range 0.5-150 mg L^-1 with coefficients of determination up to 0.9979, limits of detection (LODs) and limits of quantification (LOQs) ranging from 0.02 to 0.05 mg L^-1 and from 0.06 to 0.17 mg L^-1, respectively, precision below 14.7 mg L^-1, and recoveries from wastewater samples in the range of 66.1-99.9%. The developed methodologies are simpler, faster, and require less sample and solvent volumes than conventional methodologies, having a lower impact on the environment. Nevertheless, the μSPEed approach was found to be more efficient, easier to perform, and with a higher greener profile. This study highlights the potential of microextraction techniques for the analysis of pesticide residues in food and environmental samples. Overall, it presents a fast and efficient method for the analysis of pesticides in wastewater samples, which can be useful for monitoring and controlling pesticide contamination in the environment.

Determination of Ethylene Glycol Dinitrate in Environmental and Forensic Water Samples Using Microextraction by Packed Sorbent Followed by Gas Chromatography

Ethylene glycol dinitrate (EGDN) is a liquid nitrate ester, a secondary explosive. In the past, it was used as an explosive ingredient in dynamite along with nitroglycerine. Due to its various applications, the reliable detection of EGDN in the environment is a key issue for both forensic and environmental applications. In these areas, sensitive and reliable methods for determining the concentration of nitro compounds are needed. Microextraction by packed sorbent (MEPS) is an innovative approach to green technology in the sample preparation field. Compared to conventional solid-phase extraction (SPE), MEPS uses a smaller sample volume and can be easily combined with various chromatographic techniques. An important benefit is the reduction of sorbent amount and up to 100-times repeatable use compared to disposable SPE columns, thus reducing the costs of analysis as well as waste production. Optimal extraction parameters for isolating EGDN from water, e.g., 30 µL of toluene as extraction agent, working in one cycle and in draw/discard mode, were selected. Method validation was performed, obtaining a limit of detection and a limit of quantification of 0.45 pg/μL and 1.34 pg/μL, respectively. Accuracy in terms of recovery rates was evaluated over a wide concentration range, obtaining values from 83.7 to 90.0%. The satisfactory linearity expressed by the coefficient of determination was 0.9914. A matrix factor of −9.3% indicates a weak matrix effect. The application to real environmental water samples and a forensic post-blast wash water sample was realized. EGDN detection in the post-blast samples provides valuable information for forensic technicians.

Capsule Phase Microextraction Combined with Chemometrics for the HPLC Determination of Amphotericin B in Human Serum

This article discusses the use of a sorbent-based microextraction technique employing a capsule device to isolate amphotericin B (AMB) from human serum before analysis by high performance liquid chromatography (HPLC). AMB is a macrocyclic compound used for the treatment of invasive fungal infections. Before determining AMB in human serum by HPLC, a sample preparation step is required. Capsule phase microextraction (CPME) integrates the stirring and filtration mechanisms in a single unit, simplifying the sample preparation procedure. Moreover, it results in fast extraction kinetics and high extraction efficiency, while it has proved to be a powerful tool for bioanalysis. Different sol–gel sorbent encapsulated microextraction capsules were investigated, and sol–gel Carbowax 20 M was finally chosen as the basis for the microextraction device. Accordingly, the sample preparation protocol was investigated using a face-centered central composite design to achieve good extraction performance. The optimum protocol was validated in terms of linearity, selectivity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. The linear range of the developed approach was 0.10–10.0 μg mL−1. The LOD value was 0.03 μg mL−1, and the LOQ value was 0.10 μg mL−1. Method accuracy (expressed as relative recovery) was 87–113%, while the relative standard deviation of the repeatability (sr) and within-laboratory reproducibility (sR) were <12.4%. The sol–gel sorbent encapsulated microextraction capsules were reusable for at least 10 extraction cycles. All things considered, the proposed method exhibited good overall performance, and it could be used in bioanalysis for quality control, therapeutic drug monitoring and research purposes.

The Determination of Cannabinoids in Urine Samples Using Microextraction by Packed Sorbent and Gas Chromatography-Mass Spectrometry

Cannabis is the most consumed illicit drug worldwide, and its legal status is a source of concern. This study proposes a rapid procedure for the simultaneous quantification of Δ9-tetrahydrocannabinol (THC), 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), cannabidiol (CBD), and cannabinol (CBN) in urine samples. Microextraction by packed sorbent (MEPS) was used to pre-concentrate the analytes, which were detected by gas chromatography–mass spectrometry. The procedure was previously optimized, and the final conditions were: conditioning with 50 µL methanol and 50 µL of water, sample load with two draw–eject cycles, and washing with 310 µL of 0.1% formic acid in water with 5% isopropanol; the elution was made with 35 µL of 0.1% ammonium hydroxide in methanol. This fast extraction procedure allowed quantification in the ranges of 1–400 ng/mL for THC and CBD, 5–400 ng/mL for CBN and 11-OH-THC, and 10–400 ng/mL for THC-COOH with coefficients of determination higher than 0.99. The limits of quantification and detection were between 1 and 10 ng/mL using 0.25 mL of sample. The extraction efficiencies varied between 26 and 85%. This analytical method is the first allowing the for determination of cannabinoids in urine samples using MEPS, a fast, simple, and low-cost alternative to conventional techniques.

A Review of Extraction Methods and Analytical Techniques for Styrene and its Metabolites in Biological Matrices

We reviewed the toxicokinetics of styrene to introduce reliable surrogates for biological monitoring of styrene workers. Also, extraction techniques and analytical methods for styrene and its metabolites have been discussed. Sample preparation is the main bottleneck of the analytical techniques for styrene and its metabolites. While some microextraction methods have been developed to overcome such drawbacks, some still have limitations such as long extraction time, fiber swelling and breakage, and the cost and the limited lifetime of the fiber. Among all, microextraction by packed sorbents coupled with high performance liquid chromatography with ultraviolet detection (MEPS-HPLC-UV) can be the method of choice for determining styrene metabolites. Few studies investigated unchanged styrene in breath samples. Chemical determination in exhaled breath provides new insights into organ toxicity in workers with inhalation exposures and can be considered as a fascinating tool in risk assessment strategies. Taking blood samples is invasive and less accepted by workers than other samples. In contrast, breath analysis is the most attractive method for workers because breath samples are easy to collect and non-invasive, and does not require worker transfer to health facilities. Therefore, developing selective and sensitive methods for determining styrene in breath samples is recommended for future studies.

Identification of volatile producing enzymes in higher fungi: Combining analytical and bioinformatic methods

Filamentous fungi harbor the genetic potential for the biosynthesis of several secondary metabolites including various volatile organic compounds (VOCs). Nonetheless, under standard laboratory conditions, many of these VOCs are not formed. Furthermore, little is known about enzymes involved in the production of fungal VOCs. To tap these interesting topics, we developed an approach to identify enzymes putatively involved in the fungal VOC biosynthesis. In this chapter, we highlight different fungal cultivation methods and techniques for the extraction of VOCs, including a method that allows the noninvasive analysis of VOCs. In addition using terpene synthases as an example, it is depicted how enzymes putatively involved in VOC synthesis can be identified by means of bioinformatic approaches. Transcriptomic data of chosen genes combined with volatilome data obtained during different developmental stages is demonstrated as a powerful tool to identify enzymes putatively involved in fungal VOC biosynthesis. Especially with regard to subsequent enzyme characterization, this procedure is a target-oriented way to save time and efforts by considering only the most important enzymes.

Solventless Microextration Techniques for Pharmaceutical Analysis: The Greener Solution

Extensive efforts have been made in the last decades to simplify the holistic sample preparation process. The idea of maximizing the extraction efficiency along with the reduction of extraction time, minimization/elimination of hazardous solvents, and miniaturization of the extraction device, eliminating sample pre- and posttreatment steps and reducing the sample volume requirement is always the goal for an analyst as it ensures the method’s congruency with the green analytical chemistry (GAC) principles and steps toward sustainability. In this context, the microextraction techniques such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), fabric phase sorptive extraction (FPSE), in-tube extraction dynamic headspace (ITEX-DHS), and PAL SPME Arrow are being very active areas of research. To help transition into wider applications, the new solventless microextraction techniques have to be commercialized, automated, and validated, and their operating principles to be anchored to theory. In this work, the benefits and drawbacks of the advanced microextraction techniques will be discussed and compared, together with their applicability to the analysis of pharmaceuticals in different matrices.

Metabolic Profiling and Quantitative Analysis of Cerebrospinal Fluid Using Gas Chromatography-Mass Spectrometry: Current Methods and Future Perspectives

Cerebrospinal fluid is a key biological fluid for the investigation of new potential biomarkers of central nervous system diseases. Gas chromatography coupled to mass-selective detectors can be used for this investigation at the stages of metabolic profiling and method development. Different sample preparation conditions, including extraction and derivatization, can be applied for the analysis of the most of low-molecular-weight compounds of the cerebrospinal fluid, including metabolites of tryptophan, arachidonic acid, glucose; amino, polyunsaturated fatty and other organic acids; neuroactive steroids; drugs; and toxic metabolites. The literature data analysis revealed the absence of fully validated methods for cerebrospinal fluid analysis, and it presents opportunities for scientists to develop and validate analytical protocols using modern sample preparation techniques, such as microextraction by packed sorbent, dispersive liquid-liquid microextraction, and other potentially applicable techniques.

An Overview of Pretreatment and Analysis of Nucleotides in Different Samples (Update since 2010)

Nucleotides, which are important low-molecular-weight compounds present in organisms, are precursors of nucleic acids and participate in various regulatory and metabolic functions. Sensitive and valid methods for monitoring and determining nucleotides and nucleosides in different samples are urgently required. Due to the presence of numerous endogenous interferences in complex matrices and the high polarity of the molecules of the phosphate moiety, the determination of nucleotide content is challenging. This review summarizes the pretreatment and analysis methods of nucleotides in different samples. Advanced pretreatment methods, including different microextraction methods, solid-phase extraction based on novel materials, QuEChERS, are clearly displayed, and continuous progress which has been made in LC, LC-MS/MS and capillary electrophoresis methods are discussed. Moreover, the strengths and weaknesses of different methods are discussed and compared. Highlight:Advanced pretreatment and detection methods of nucleotides were critically reviewed.Microextraction technology was one of the trends of nucleotides pretreatment in the future.Applications of novel materials and supercritical fluid were highlighted.The evolution and advance of HRMS analyzers were in detailed.

[Research progress of microextraction by packed sorbent and its application in microvolume sample extraction]

Microextraction is a rapidly developing sample preparation technology in the field of analytical chemistry, which is seeing widespread application. Accurate sample preparation can not only save time but also improve the efficiency of analysis, determination, and data quality. At present, sample pretreatment methods must be rapid, allow for miniaturization, automation, and convenient online connection with analytical instruments. To meet the requirements of green analytical methods and improve the extraction efficiency, microextraction techniques have been introduced as suitable replacements to conventional sample preparation and extraction methods. Microextraction using a packed sorbent (MEPS) is a new type of sample preparation technology. The MEPS equipment was prepared using microsyringe with a volume of 50-500 μL, including MEPS syringes and MEPS adsorption beds (barrel insert and needle, BIN), which is essentially similar to a miniaturized solid phase extraction device. The BIN contains the adsorbent and is built into the syringe needle. A typical MEPS extraction procedure involves repeatedly pumping the sample solution in two directions (up and down) through the adsorbent multiple times in the MEPS syringe. The specific operation course of MEPS includes conditioning, loading, washing, elution, and introduction into the analysis instrument. The conditioning process is adopted to infiltrate the dry sorbent and remove bubbles between the filler particles. The adsorption process is accomplished by pulling the liquid plunger of the syringe so that the sample flows through the adsorbent in both directions multiple times. The washing process involves rinsing the sorbent to remove unwanted components after the analyte is retained. The elution process involves the use of an eluent to ensure that the sample flows through the adsorbent in both directions multiple times, so that elution can be realized by the pumping-pushing action. The target analyte is eluted with the eluent, which can be directly used for chromatographic analysis. However, when processing complex biological matrix samples by MEPS, pretreatment steps such as dilution of the sample and removal of proteins are commonly required. At present, the operation modes of the MEPS equipment are classified into three types: manual, semi-automated, and fully automated. This increase in the degree of automation is highly conducive to processing extremely low or extremely high sample volumes. Critical factors affecting the MEPS performance have been investigated in this study. The conditions for MEPS optimization are the operating process parameters, including sample flow rate, sample volume, number of sample extraction cycles, type and volume of the adsorbent, and elution solvents. It is also necessary to consider the effect of the sample matrix on the performance of MEPS. The MEPS sorbent should be cleaned by a solvent to eliminate carryover and reuse. The sorbent is a core aspect of MEPS. Several types of commercial and non-commercial sorbents have been used in MEPS. Commercial sorbents include silica-based sorbents such as unmodified silica (SIL), C2, C8, and C18. Unmodified silicon-based silica is a normal phase adsorption material, which is highly polar and can be used to retain polar analytes. C18, C8, and C2 materials are suitable for reversed-phase adsorption, while SCX, SAX, APS, and M1 (C8+SCX) adsorbents are suitable for the mixed-mode and ion-exchange modes. Noncommercial sorbents include molecularly imprinted materials, restricted-access molecularly imprinted materials, graphitized carbon, conductive polymer materials, modified silicon materials, and covalent-organic framework materials. The performance of MEPS has recently been illustrated by online with LC-MS and GC-MS assays for the analysis of biological matrices, environmental samples, and food samples. Pretreatment in MEPS protocols includes dilution, protein precipitation, and centrifugation in biological fluid matrices. Because of the small sample size, fast operation, etc., MEPS is expected to be more widely used in the analysis of bio-matrix samples. MEPS devices could also play an important role in field pretreatment and analysis.

Vacuum microwave dehydration decreases volatile concentration and soluble protein content of pea (Pisum sativum L.) protein

BACKGROUND

Peas are an inexpensive yet nutritious and sustainable source of protein. However, it is challenging to incorporate pea proteins into food formulations owing to their beany or green off-flavours and their limited water solubility.

RESULTS

Vacuum microwave dehydration (VMD) of pea protein with an initial moisture content of 425% (dry basis, db) at 2 W g-1 specific microwave energy and 200 Torr vacuum level for 88 min led to an 83% reduction in total volatile compound concentration. VMD processing at high initial moisture contents facilitated the Maillard reaction, enhancing the extent of protein cross-linking, leading to a marked decrease in soluble protein content, to 11 g kg-1 . Reducing the initial moisture content to 56% db greatly retained protein solubility (112-113 g kg-1 ), but it only led to a minor reduction in total volatile compound concentration (2-11% reduction). A high microwave energy (20 W g-1 )-short time (2 min) treatment at 200 Torr vacuum level was found optimal, reducing both volatile levels and soluble protein content by ~50%.

CONCLUSION

Evidently, it is difficult to employ VMD without reduction of pea protein solubility and corresponding changing in functionality. Yet, if optimized, VMD has the capability to decrease volatile concentrations while retaining protein solubility. Future sensory analysis should be conducted to determine whether the aforementioned reductions in total volatile compound concentration may have a notable effect on consumer palatability. © 2020 Society of Chemical Industry.

Thin Porous Poly(ionic liquid) Coatings for Enhanced Headspace Solid Phase Microextraction

In this contribution, thin poly(ionic liquid) (PIL) coatings with a well-defined pore structure built up from interpolyelectrolyte complexation between a PIL and poly(acrylic acid) (PAA) were successfully used for enhanced solid phase microextraction (SPME). The introduction of porosity with tunable polarity through the highly versatile PIL chemistry clearly boosts the potential of SPME in the detection of compounds at rather low concentrations. This work will inspire researchers to further explore the potential of porous poly(ionic liquid) materials in sensing and separation applications.

Unravelling the Potential of Salivary Volatile Metabolites in Oral Diseases. A Review

Fostered by the advances in the instrumental and analytical fields, in recent years the analysis of volatile organic compounds (VOCs) has emerged as a new frontier in medical diagnostics. VOCs analysis is a non-invasive, rapid and inexpensive strategy with promising potential in clinical diagnostic procedures. Since cellular metabolism is altered by diseases, the resulting metabolic effects on VOCs may serve as biomarkers for any given pathophysiologic condition. Human VOCs are released from biomatrices such as saliva, urine, skin emanations and exhaled breath and are derived from many metabolic pathways. In this review, the potential of VOCs present in saliva will be explored as a monitoring tool for several oral diseases, including gingivitis and periodontal disease, dental caries, and oral cancer. Moreover, the analytical state-of-the-art for salivary volatomics, e.g., the most common extraction techniques along with the current challenges and future perspectives will be addressed unequivocally.

Green Approaches to Sample Preparation Based on Extraction Techniques

Preparing a sample for analysis is a crucial step of many analytical procedures. The goal of sample preparation is to provide a representative, homogenous sample that is free of interferences and compatible with the intended analytical method. Green approaches to sample preparation require that the consumption of hazardous organic solvents and energy be minimized or even eliminated in the analytical process. While no sample preparation is clearly the most environmentally friendly approach, complete elimination of this step is not always practical. In such cases, the extraction techniques which use low amounts of solvents or no solvents are considered ideal alternatives. This paper presents an overview of green extraction procedures and sample preparation methodologies, briefly introduces their theoretical principles, and describes the recent developments in food, pharmaceutical, environmental and bioanalytical chemistry applications.

Saliva as a non-invasive tool for monitoring oxidative stress in swimmers athletes performing a VO2max cycle ergometer test

Biomarkers of oxidative stress are generally measured in blood and its derivatives. However, the invasiveness of blood collection makes the monitoring of such chemicals during exercise not feasible. Saliva analysis is an interesting approach in sport medicine because the collection procedure is easy-to-use and does not require specially-trained personnel. These features guarantee the collection of multiple samples from the same subject in a short span of time, thus allowing the monitoring of the subject before, during and after physical tests, training or competitions. The aim of this work was to evaluate the possibility of following the changes in the concentration of some oxidative stress markers in saliva samples taken over time by athletes under exercise. To this purpose, ketones (i.e. acetone, 2-butanone and 2-pentanone), aldehydes (i.e. propanal, butanal, and hexanal), α,β-unsaturated aldehydes (i.e. acrolein and methacrolein) and di-carbonyls (i.e. glyoxal and methylglyoxal) were derivatized with 2,4-dinitrophenylhydrazine, and determined by ultra-high performance liquid chromatography coupled to diode array detector. Prostaglandin E₂, F₂/E₂-isoprostanes, F₂-dihomo-isoprostanes, F₄-neuroprostanes, and F₂-dihomo-isofuranes were also determined by a reliable analytical procedure that combines micro-extraction by packed sorbent and ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometry. Overall the validation process showed that the methods have limits of detection in the range of units of ppb for carbonyls and tens to hundreds of ppt for isoprostanes and prostanoids, very good quantitative recoveries (90-110%) and intra- and inter-day precision lower than 15%. The proof of applicability of the proposed analytical approach was investigated by monitoring the selected markers of oxidative stress in ten swimmers performing a VO_2max cycle ergo meter test. The results highlighted a clear increase of salivary by-products of oxidative stress during exercise, whereas a sharp decrease, approaching baseline values, of these compounds was observed in the recovery phase. This study opens up a new approach in the evaluation of oxidative stress and its relation to aerobic activity.

Rapid Identification Method for Gamma-Irradiated Soybeans Using Gas Chromatography-Mass Spectrometry Coupled with a Headspace Solid-Phase Microextraction Technique

This study evaluated the applicability of a rapid analytical method using a headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS) technique to identify gamma-irradiated soybeans (0.1-5 kGy). From the partial least squares discriminant analysis used to discriminate between non-irradiated and irradiated soybean samples, 1,7-hexadecadiene was selected as the identifying marker. Response surface methodology experiments were used to determine the optimal HS-SPME extraction conditions including a carboxen/polydimethylsiloxane fiber with an extraction temperature of 98 °C and an extraction time of 55 min. 1,7-Hexdecadiene was detected in all samples irradiated at ≥ 0.1 kGy under the optimized HS-SPME-GC/MS conditions, and the unique presence of the marker in a gamma-irradiated sample was verified by comparing the results from heat, steam, microwave, sonication, and ultraviolet treatments. The comparisons of the identification properties for various conventional methods validated several advances in HS-SPME-GC/MS analysis in terms of rapid analysis, high sensitivity, and absence of solvent.

Application of HS-SPME-GC-MS for the analysis of aldehydes produced by different insect species and their antifungal activity

In this study, a procedure was developed to determine aldehydes using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography (GC) coupled with mass spectrometry (MS). The aldehydes selected for research had previously been identified in various species of insects. Minimal inhibitory concentrations of the compounds against strains of entomopathogenic fungi were also determined. At the outset, the best SPME extraction conditions were chosen for the analysis to obtain good chromatographic separation. The analysis was carried out using a BZ-5 column and different SPME fibers were used to isolate the aldehydes. DVB/CAR/PDMS fiber appeared to be the most efficient coating for undertaking the measurements. The best parameters of separation by HS-SPME and analysis by GC-MS were selected. In addition, the aldehydes were tested for their potential antifungal activity. A procedure was developed to determine the aldehydes using HS-SPME-GC-MS. Heptanal, 2,4-nonadienal, 2-decenal and undecanal were the most effective antifungal compounds against entomopathogenic fungi.

Microextraction of aromatic microbial metabolites by packed hypercrosslinked polystyrene from blood serum

The article is devoted to the application of modern sample preparation technique - microextraction by packed sorbent (MEPS) - in conjunction with non-conventional type of sorbent - hypercrosslinked polystyrene, that was investigated for the first time in this work. Their combination was used to extract phenylcarboxylic acid-type aromatic microbial metabolites from serum samples of a healthy volunteer with following derivatization and GC-MS detection. As barrel insert and needle for MEPS with hypercrosslinked polystyrene is not produced, we designed a device to imitate the commercial MEPS system with packed granular biporous hypercrosslinked polystyrene. Nine aromatic microbial metabolites, including sepsis associated phenyllactic, 4-hydroxyphenyllactic and 4-hydroxyphenylacetic acids, were extracted from serum samples (recoveries were 20-70%) and a linear dependence was revealed in the most clinically significant range of concentrations (0.5-18 μM). The results obtained demonstrate the perspective of the applying of hypercrosslinked polystyrene in commercial devices for MEPS for the future analyses of biological samples, in particular for the early diagnosis of sepsis and treatment effectiveness control.

Multi-walled Carbon Nanotubes Reinforced into Hollow Fiber by Chitosan Sol-gel for Solid/Liquid Phase Microextraction of NSAIDs from Urine Prior to HPLC-DAD Analysis

Background:

The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies.

Methods:

In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC–DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution.

Results:

The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods.

Conclusion:

The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.

Aroma Profile Analyses of Filamentous Fungi Cultivated on Solid Substrates

Filamentous fungi have been used since centuries in the production of food by means of solid substrate fermentation (SSF). The most applied SSF involving fungi is the cultivation of mushrooms, e.g., on tree stumps or sawdust, for human consumption. However, filamentous fungi are also key players during manufacturing of several processed foods, like mold cheese, tempeh, soy sauce, and sake. In addition to their nutritive values, these foods are widely consumed due to their pleasant flavors. Based on the potentials of filamentous fungi to grow on solid substrates and to produce valuable aroma compounds, in recent decades, several studies concentrated on the production of aroma compounds with SSF, turning cheap agricultural wastes into valuable flavors. In this review, we focus on the presentation of common analytical methods for volatile substances and highlight various applications of SSF of filamentous fungi dealing with the production of aroma compounds. Graphical Abstract.

Current trends on microextraction by packed sorbent – fundamentals, application fields, innovative improvements and future applications

MEPS, the acronym of microextraction by packed sorbent, is a simple, fast and user- and environmentally-friendly miniaturization of the popular solid-phase extraction technique (SPE).

Urinary volatile organic compounds in overweight compared to normal-weight children: results from the Italian I.Family cohort

Accumulating evidence shows that urinary volatile organic compounds (VOCs) could be perturbed in many physiological and pathological states, including several diseases and different dietary exposures. Few studies investigated the urinary metabolic signature associated to excess body weight and obesity in adult populations, while a different VOCs profile was found in exhaled breath in obese as compared to lean children. Aim of this study was to evaluate the VOCs profile in the urine of 21 overweight/obese (OW/Ob) and 28 normal-weight (NW) children belonging to the Italian cohort of the I. Family study. Urine samples were analysed by Solid Phase Micro-Extraction (SPME) GC-MS under both acidic and alkaline conditions, in order to profile a wider range of urinary volatiles with different physicochemical properties. Multivariate statistics techniques were applied to bioanalytical data to visualize clusters of cases and detect the VOCs able to differentiate OW/Ob from NW children. Under alkaline conditions, fourteen VOCs were identified, distinguishing OW/Ob from NW children. Our results suggest that VOCs signatures differ between OW/Ob and NW children. However, the biological and pathophysiological meaning of the observed differences needs to be elucidated, in order to better understand the potential of urinary VOCs as early metabolic biomarkers of obesity.

Heat-stabilised rice bran consumption by colorectal cancer survivors modulates stool metabolite profiles and metabolic networks: a randomised controlled trial

Rice bran (RB) consumption has been shown to reduce colorectal cancer (CRC) growth in mice and modify the human stool microbiome. Changes in host and microbial metabolism induced by RB consumption was hypothesised to modulate the stool metabolite profile in favour of promoting gut health and inhibiting CRC growth. The objective was to integrate gut microbial metabolite profiles and identify metabolic pathway networks for CRC chemoprevention using non-targeted metabolomics. In all, nineteen CRC survivors participated in a parallel randomised controlled dietary intervention trial that included daily consumption of study-provided foods with heat-stabilised RB (30 g/d) or no additional ingredient (control). Stool samples were collected at baseline and 4 weeks and analysed using GC-MS and ultra-performance liquid chromatography-MS. Stool metabolomics revealed 93 significantly different metabolites in individuals consuming RB. A 264-fold increase in β-hydroxyisovaleroylcarnitine and 18-fold increase in β-hydroxyisovalerate exemplified changes in leucine, isoleucine and valine metabolism in the RB group. A total of thirty-nine stool metabolites were significantly different between RB and control groups, including increased hesperidin (28-fold) and narirutin (14-fold). Metabolic pathways impacted in the RB group over time included advanced glycation end products, steroids and bile acids. Fatty acid, leucine/valine and vitamin B₆ metabolic pathways were increased in RB compared with control. There were 453 metabolites identified in the RB food metabolome, thirty-nine of which were identified in stool from RB consumers. RB consumption favourably modulated the stool metabolome of CRC survivors and these findings suggest the need for continued dietary CRC chemoprevention efforts.

Evaluation of microextraction by packed sorbent, liquid-liquid microextraction and derivatization pretreatment of diet-derived phenolic acids in plasma by gas chromatography with triple quadrupole mass spectrometry

Miniaturized sample pretreatments for the analysis of phenolic metabolites in plasma, involving protein precipitation, enzymatic deconjugation, extraction procedures, and different derivatization reactions were systematically evaluated. The analyses were conducted by gas chromatography with mass spectrometry for the evaluation of 40 diet-derived phenolic compounds. Enzyme purification was necessary for the phenolic deconjugation before extraction. Trimethylsilanization reagent and two different tetrabutylammonium salts for derivatization reactions were compared. The optimum reaction conditions were 50 μL of trimethylsilanization reagent at 90°C for 30 min, while tetrabutylammonium salts were associated with loss of sensitivity due to rapid activation of the inert gas chromatograph liner. Phenolic acids extractions from plasma were optimized. Optimal microextraction by packed sorbent performance was achieved using an octadecylsilyl packed bed and better recoveries for less polar compounds, such as methoxylated derivatives, were observed. Despite the low recovery for many analytes, repeatability using an automated extraction procedure in the gas chromatograph inlet was 2.5%. Instead, using liquid-liquid microextraction, better recoveries (80-110%) for all analytes were observed at the expense of repeatability (3.8-18.4%). The phenolic compounds in gerbil plasma samples, collected before and 4 h after the administration of a calafate extract, were analyzed with the optimized methodology.