In vivo and ex vivo SPME: a low invasive sampling and sample preparation tool in clinical bioanalysis

Evaluation of thin film microextraction based on graphene oxide/ polymer composite: Experimental and theoretical insights

Experimental and theoretical assessments of a graphene oxide-based polymer as adsorbent for thin film microextraction (TFME) were conducted as part of this research. Graphene oxide (GO) was embedded in the organic polymer poly(styrene-co-divinylbenzene) (PS-DVB) to prepare a sorbent suitable for direct-immersion TFME. A TFME membrane coating prepared with the GO/PS-DVB sorbent and polydimethylsiloxane (PDMS) as binder was then applied for extraction of organic pollutants from aqueous and gaseous samples. The surface morphology of the TFME coating was examined by scanning electron microscopy (SEM). Various TFME parameters influencing extraction efficiency, such as extraction time and temperature, desorption temperature, and ionic strength, were investigated and optimized. In a comparison of TFME membranes, the GO/PS-DVB/PDMS TFME membrane was shown to yield higher extraction efficiencies for the targeted analytes than the pure PDMS and DVB/PDMS TFME membranes. The calibration graphs of the organic pollutants displayed linearity for most of the target analytes within the 10-2000 ng L-1 concentration range. The repeatability (RSD %, n = 5) and reproducibility (RSD %, n = 3) of the method were in the ranges of 2.2-5.9 %, and 3.2-8.5 %, respectively, at a concentration level of 500 ng L-1, whereas accuracy (%) ranged between 79.8 and 119 %. The developed method was successfully applied for determinations of organic pollutants in tap water, lake water, and wastewater samples. Furthermore, the impact of mass transfer kinetics on extractions by the GO/PS-DVB/PDMS TFME membrane from gaseous samples was theoretically discussed and experimentally verified. The results of this work demonstrate that the GO/PS-DVB/PDMS TFME method is a simple, efficient, and environmentally friendly method for pre-treatment of organic pollutants.

Recent advances in the use of SPME for drug analysis in clinical, toxicological, and forensic medicine studies

Solid-phase microextraction (SPME) has gained attention as a simple, fast, and non-exhaustive extraction technique, as its unique features enable its use for the extraction of many classes of drugs from biological matrices. This sample-preparation approach consolidates sampling and sample preparation into a single step, in addition to providing analyte preconcentration and sample clean-up. These features have helped SPME become an integral part of several analytical protocols for monitoring drug concentrations in human matrices in clinical, toxicological, and forensic medicine studies. Over the years, researchers have continued to develop the SPME technique, resulting in the introduction of novel sorbents and geometries, which have resulted in improved extraction efficiencies. This review summarizes developments and applications of SPME published between 2016 and 2022, specifically in relation to the analysis of central nervous system drugs, drugs used to treat cardiovascular disorders and bacterial infections, and drugs used in immunosuppressive and anticancer therapies.

In vivo solid phase microextraction for therapeutic monitoring and pharmacometabolomic fingerprinting of lung during in vivo lung perfusion of FOLFOX

In vivo lung perfusion (IVLP) is a novel isolated lung technique developed to enable the local, in situ administration of high-dose chemotherapy to treat metastatic lung cancer. Combination therapy using folinic acid (FOL), 5-fluorouracil (F), and oxaliplatin (OX) (FOLFOX) is routinely employed to treat several types of solid tumours in various tissues. However, F is characterized by large interpatient variability with respect to plasma concentration, which necessitates close monitoring during treatments using of this compound. Since plasma drug concentrations often do not reflect tissue drug concentrations, it is essential to utilize sample-preparation methods specifically suited to monitoring drug levels in target organs. In this work, in vivo solid-phase microextraction (in vivo SPME) is proposed as an effective tool for quantitative therapeutic drug monitoring of FOLFOX in porcine lungs during pre-clinical IVLP and intravenous (IV) trials. The concomitant extraction of other endogenous and exogenous small molecules from the lung and their detection via liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) enabled an assessment of FOLFOX's impact on the metabolomic profile of the lung and revealed the metabolic pathways associated with the route of administration (IVLP vs. IV) and the therapy itself. This study also shows that the immediate instrumental analysis of metabolomic samples is ideal, as long-term storage at -80 °C results in changes in the metabolite content in the sample extracts.

Performance Evaluation of Extraction Coatings with Different Sorbent Particles and Binder Composition

Binders are critical components used in the preparation of a range of extraction devices, including solid-phase microextraction (SPME) devices. While the main role of a binder is to affix the sorbent particles to the selected support, it is critical to select the optimal binder to ensure that it does not negatively impact the coating's particle sorption capability. This work presents the first comprehensive investigation of the interactions between binders and solid sorbent particles as these interactions can significantly impact the performance of the coating. Specifically, the findings presented herein provide a better understanding of the extraction mechanisms of composite coatings and new rules for predicting the particle adhesion forces and binder distribution in the coating. The influence of binder chemistry on coating performance is investigated by examining a selection of the most used binders, namely, polydimethylsiloxane (PDMS), polyacrylonitrile (PAN), poly(vinylidene difluoride) (PVDF), polytetrafluoroethylene amorphous fluoroplastics (PTFE AF 2400), and polybenzimidazole (PBI). The solid particles (e.g., hydrophilic-lipophilic balanced (HLB) and C18) used in this work were selected for their ability to provide optimal extraction coverage for a broad range of analytes. The results show that PDMS does not change the properties of the solid particles and that the binder occupies a negligible volume due to shrinking after polymerization, resulting in the solid particles making up most of the coating volume. Hence, the coating sorption characteristics correspond closely to the properties of the selected solid particles. On the other hand, the results also showed that PTFE AF 2400 can interact with the active surface of the sorbent, leading to the deactivation of the sorbent particles. Therefore, the extraction performance and permeability coefficients decrease as the size of the penetrant increases, indicating a rigid porous structure. The results of this study can aid in the optimization of SPME devices as they provide reference values that can be used to determine the optimal binder and the sorbent affinity for the targeted compounds. Finally, the present work also provides the broader scientific community with a strategy for investigating the properties of sorbent particle/binder structures and defines the characteristics of a good coating/membrane by analyzing all parameters such as kinetics, thermodynamic equilibria, and morphology.

Non-invasive Sampling of Human Body Fluids Using In Vivo SPME

Noninvasive body fluids offer attractive sources to gain insights into human health. The in vivo solid-phase microextraction (SPME) technique is a fast and versatile sample preparation technique for the noninvasive sampling of human body fluids in various fields. This chapter summarizes the applications of SPME coupled with mass spectrometry (MS)-based approaches for noninvasive investigations of human body fluids, including urine, sweat, and saliva. New features of noninvasive SPME sampling and MS-based analysis are highlighted, and the prospects on their further development are also discussed.

Untargeted Metabolomic Assay of Prefrail Older Adults after Nutritional Intervention

Frailty is a geriatric syndrome causing a reduction in the body’s functional reserves. Proper nutrition may be helpful in delaying transitioning older adults from pre-frail to frailty syndrome. The present study evaluates the nutritional status of pre-frail patients who underwent nutritional intervention and metabolomic changes resulting from this intervention. Sixteen pre-frail patients (68.4 ± 5.5 years old; 81.3% women) were enrolled for nutritional intervention, and twenty-nine robust elderly people (69.3 ± 5.3 years old; 82.8% women) were the control group. Pre-frail patients consumed 1.0 g protein/kg BW/day for eight weeks through diet modification and an additional daily intake of a protein powder formula. Taken measurements included: Nutritional anthropometry, assessment of food intake, and blood serum analysis with an untargeted metabolomic assessment. Protein consumption increased by 25.8%; moreover, significant increases in body weight (+1.2 kg; p = 0.023) and muscle mass index (+0.1 kg/m²; p = 0.042) were also observed. The untargeted metabolomic assay showed a significant increase in arachidonic acid (p = 0.038), and valine (p = 0.008) among pre-frail patients. Increased protein consumption is reflected in improved anthropometric and biochemical parameters of pre-frail patients. Moreover, metabolomic assay can be a useful tool in determining compliance with dietary recommendations.

Microsampling with a Solid-Phase Extraction Cartridge: Storage and Online Mass Spectrometry Analysis

This study aims to introduce the concept of utilizing a solid-phase extraction (SPE) cartridge for remote biofluid collection, followed by direct sample analysis at a later time. For this, a dried matrix spot was prepared in a syringe, in the form of SPE cartridge for the first time to enable small biofluid collection (microsampling), storage, shipment, and online electrospray ionization (ESI) mass spectrometry (MS) analysis of the stored dried samples. The SPE sorbents were packed into an ESI syringe and the resultant cartridge was used for sampling small volumes (<20 μL) of different complex biological fluids including blood, plasma, serum, and urine. The collected sample was stored in the dry state within the confinement of the SPE sorbent at room temperature, and analyte stability (e.g., diazepam) was maintained for more than a year. Direct coupling of the SPE cartridge to MS provides excellent accuracy, precision, and sensitivity for analyzing illicit drugs present in the biofluid. The corresponding mechanism of wrong-way positive ion generation from highly basic elution solvents was explored. Without chromatography, our direct SPE-ESI-MS analysis technique afforded detection limits as low as 26 and 140 pg/mL for raw urine and untreated plasma, respectively. These promising results proved that the new syringe-based SPE cartridge can serve as a good alternative to conventional microsampling techniques in terms of analyte stability, ease of operation and versatility, and analytical sensitivity and speed.

Solid phase microextraction chemical biopsy tool for monitoring of doxorubicin residue during in vivo lung chemo-perfusion

Development of a novel in vivo lung perfusion (IVLP) procedure allows localized delivery of high-dose doxorubicin (DOX) for targeting residual micrometastatic disease in the lungs. However, DOX delivery via IVLP requires careful monitoring of drug level to ensure tissue concentrations of this agent remain in the therapeutic window. A small dimension nitinol wire coated with a sorbent of biocompatible morphology (Bio-SPME) has been clinically evaluated for in vivo lung tissue extraction and determination of DOX and its key metabolites. The in vivo Bio-SPME-IVLP experiments were performed on pig model over various (150 and 225 mg/m²) drug doses, and during human clinical trial. Two patients with metastatic osteosarcoma were treated with a single 5 and 7 μg/mL (respectively) dose of DOX during a 3-h IVLP. In both pig and human cases, DOX tissue levels presented similar trends during IVLP. Human lung tissue concentrations of drug ranged between 15 and 293 μg/g over the course of the IVLP procedure. In addition to DOX levels, Bio-SPME followed by liquid chromatography-mass spectrometry analysis generated 64 metabolic features during endogenous metabolite screening, providing information about lung status during drug administration. Real-time monitoring of DOX levels in the lungs can be performed effectively throughout the IVLP procedure by in vivo Bio-SPME chemical biopsy approach. Bio-SPME also extracted various endogenous molecules, thus providing a real-time snapshot of the physiology of the cells, which might assist in the tailoring of personalized treatment strategy.

Comparison of Metabolomic Profiles of Organs in Mice of Different Strains Based on SPME-LC-HRMS

Given that the extent to which genetics alters the metabolomic profile of tissues is still poorly understood, the current study aimed to characterize and investigate the metabolite profiles of brain, liver, kidney and skeletal muscle of two common mouse inbred strains (BALB/c, C57BL/6) and one outbred stock (CD1) for strain-specific differences. Male mice (n = 15) at the age of 12 weeks were used: BALB/c (n = 5), C57BL/6 (n = 5) and CD1 (n = 5). Solid phase microextraction (SPME) was applied for the extraction of analytes from the tissues. SPME fibers (approximately 0.2 mm in diameter) coated with a biocompatible sorbent (4 mm length of hydrophilic-lipophilic balanced particles) were inserted into each organ immediately after euthanasia. Samples were analyzed using liquid chromatography coupled to a Q-Exactive Focus Orbitrap mass spectrometer. Distinct interstrain differences in the metabolomic patterns of brain and liver tissue were revealed. The metabolome of kidney and muscle tissue in BALB/c mice differed greatly from C57BL/6 and CD1 strains. The main compounds differentiating all the targeted organs were alpha-amino acids, purine nucleotides and fatty acid esters. The results of the study indicate that the baseline metabolome of organs, as well as different metabolic pathways, vary widely among general-purpose models of laboratory mice commonly used in biomedical research.

Rapid quantification of acetaminophen in plasma using solid-phase microextraction coupled with thermal desorption electrospray ionization mass spectrometry

RATIONALE

Solid-phase microextraction coupled with thermal desorption electrospray ionization tandem mass spectrometry (SPME-TD-ESI-MS/MS) is proposed as a novel method for the rapid quantification of acetaminophen in plasma samples from a pharmacokinetics (PK) study.

METHODS

Traces of acetaminophen were concentrated on commercial fused-silica fibers coated with a polar polyacrylate (PA) polymer using direct immersion SPME. No agitation, heating, addition of salt, or adjustment of the pH of the sample solution was applied during the extraction. Any acetaminophen absorbed on the SPME fibers was subsequently desorbed and detected by TD-ESI-MS/MS.

RESULTS

Parameters of the absorption, sensitivity, reproducibility, and linearity for the SPME-TD-ESI-MS/MS method were evaluated. The time required to complete a TD-ESI-MS/MS analysis was less than 30 seconds. Matrix-matching calibration was performed to calculate the concentration of acetaminophen in the sample. A linear calibration curve with a concentration range of 100-10,000 ng/mL was constructed to calculate the quantity of acetaminophen. The SPME-TD-ESI-MS quantification results for acetaminophen in plasma were in good agreement with those obtained by the conventional LC/MS/MS method.

CONCLUSIONS

With the proposed method, a 10-min SPME time was enough to achieve the lower limit of quantitation (i.e. 100 ng/mL) and for a complete PK profiling of acetaminophen. A shorter extraction time could be achieved by applying agitation, heating, adding salt, or adjusting the pH of the sample solution to enhance analyte absorption efficiency. The time required to detect acetaminophen on the SPME fiber was less than 30 s, allowing the rapid quantification of acetaminophen in plasma with good accuracy.

Recent Advances in In Vivo SPME Sampling

In vivo solid-phase microextraction (SPME) has been recently proposed for the extraction, clean-up and preconcentration of analytes of biological and clinical concern. Bioanalysis can be performed by sampling exo- or endogenous compounds directly in living organisms with minimum invasiveness. In this context, innovative and miniaturized devices characterized by both commercial and lab-made coatings for in vivo SPME tissue sampling have been proposed, thus assessing the feasibility of this technique for biomarker discovery, metabolomics studies or for evaluating the environmental conditions to which organisms can be exposed. Finally, the possibility of directly interfacing SPME to mass spectrometers represents a valuable tool for the rapid quali- and quantitative analysis of complex matrices. This review article provides a survey of in vivo SPME applications focusing on the extraction of tissues, cells and simple organisms. This survey will attempt to cover the state-of- the-art from 2014 up to 2019.

Solid-phase microextraction: An appealing alternative for the determination of endogenous substances - A review

The determination of endogenous substances is of great significance for obtaining important biotic information such as biological components, metabolic pathways and disease biomarkers in different living organisms (e.g. plants, insects, animals and humans). However, due to the complex matrix and the trace concentrations of target analytes, the sample preparation procedure is an essential step before the analytes of interest are introduced into a detection instrument. Solid-phase microextraction (SPME), an emerging sample preparation technique that integrates sampling, extraction, concentration, and sample introduction into one step, has gained wide acceptance in various research fields, including in the determination of endogenous compounds. In this review, recent developments and applications of SPME for the determination of endogenous substances over the past five years are summarized. Several aspects, including the design of SPME devices (sampling configuration and coating), applications (in vitro and in vivo sampling), and coupling with emerging instruments (comprehensive two-dimensional gas chromatography (GC × GC), ambient mass spectrometry (AMS) and surface enhanced Raman scattering (SERS)) are involved. Finally, the challenges and opportunities of SPME methods in endogenous substances analysis are also discussed.

Coated blade spray: shifting the paradigm of direct sample introduction to MS

Coated blade spray (CBS) is a solid-phase microextraction-based technology that can be directly coupled to MS to enable the rapid qualitative and quantitative analysis of complex matrices. The goal of this mini review is to concisely introduce CBS's operational fundamentals and to consider how it correlates/contrasts with existing direct-to-MS technologies suitable for bioanalytical applications. In addition, we provide a fair comparison of CBS to other existing solid-phase microextraction-to-MS approaches, as well as an overview of recent CBS applications/strategies that have been developed to analyze diverse compounds present in biofluids.

The application of capillary microsampling in GLP toxicology studies

Aim: Capillary microsampling (CMS) to collect microplasma volumes is gradually replacing traditional, larger volume sampling from rats in GLP toxicology studies. Methodology: About 32 µl of blood is collected with a capillary, processed to plasma and stored in a 10- or 4-µl capillary which is washed out further downstream in the laboratory. CMS has been standardized with respect to materials, assay validation experiments and application for sample analysis. Conclusion: The implementation of CMS has resulted in blood volume reductions in the rat from 300 to 32 µl per time point and the elimination of toxicokinetic satellite groups in the majority of the rat GLP toxicology studies. The technique has been successfully applied in 26 GLP studies for 12 different projects thus far.

An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2–C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2–C7) generated in the bioconversion process were 0.01–1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

Ambient Ionization Mass Spectrometry for Cancer Diagnosis and Surgical Margin Evaluation

BACKGROUND

There is a clinical need for new technologies that would enable rapid disease diagnosis based on diagnostic molecular signatures. Ambient ionization mass spectrometry has revolutionized the means by which molecular information can be obtained from tissue samples in real time and with minimal sample pretreatment. New developments in ambient ionization techniques applied to clinical research suggest that ambient ionization mass spectrometry will soon become a routine medical tool for tissue diagnosis.

CONTENT

This review summarizes the main developments in ambient ionization techniques applied to tissue analysis, with focus on desorption electrospray ionization mass spectrometry, probe electrospray ionization, touch spray, and rapid evaporative ionization mass spectrometry. We describe their applications to human cancer research and surgical margin evaluation, highlighting integrated approaches tested for ex vivo and in vivo human cancer tissue analysis. We also discuss the challenges for clinical implementation of these tools and offer perspectives on the future of the field.

SUMMARY

A variety of studies have showcased the value of ambient ionization mass spectrometry for rapid and accurate cancer diagnosis. Small molecules have been identified as potential diagnostic biomarkers, including metabolites, fatty acids, and glycerophospholipids. Statistical analysis allows tissue discrimination with high accuracy rates (>95%) being common. This young field has challenges to overcome before it is ready to be broadly accepted as a medical tool for cancer diagnosis. Growing research in new, integrated ambient ionization mass spectrometry technologies and the ongoing improvements in the existing tools make this field very promising for future translation into the clinic.

Au nanoparticle decorated graphene oxide as a novel coating for solid-phase microextraction

A novel solid-phase microextraction (SPME) fiber based on a stainless steel wire coated with Au nanoparticle decorated graphene oxide was prepared using a novel protocol.