In-situ growth of covalent organic framework on stainless steel needles as solid-phase microextraction probe coupled with electrospray ionization mass spectrometry for rapid and sensitive determination of tricyclic antidepressants in biosamples

Covalent organic framework-based solid phase microextraction coupled with electrospray ionization mass spectrometry for the quantitative assessment of abnormal bile acids by triclosan exposure in mice

Bile acids, a representative diagnostic indicator of liver function, are used to visualize the extent of liver injury. Numerous studies have shown that triclosan (TCS) exposure leads to abnormal bile acid metabolism. As a result, there is a requirement to develop a fast and smart means to quantitatively monitor abnormal bile acids from exposure to triclosan in bio-sample. In this work, solid-phase microextraction (SPME) probes of sea urchin-like covalent organic frameworks (COF) were in situ synthesized on steel needles by using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) as two organic units and employed for extraction of bile acids. This TAPB-DMTP-COF-SPME possessed an excellent specified surface area (3351 m2 g-1) and a high regular porosity (∼3.6 nm), which was an ideal adsorbent to concentrate bile acids efficiently. The created probe, together with electrospray ionization mass spectrometry (ESI/MS), proved to be a fast and specific assay for the detection of bile acids in bio-samples. The proposed method had a low limitation of detection (0.03 μg L-1), good linearity (R2 ≥ 0.9931), wide linear range (0.10-1000.00 μg L-1) and excellent enrichment factor (63.60-252.00). Based on these excellent properties, it was successful application for the analyzing of bile acids in mice liver and feces, demonstrating the great potential of TAPB-DMTP-COF-SPME-ESI/MS in bile acids detection and liver injury diagnosis.

A covalent organic framework-coated steel substrate as a mass spectrometric ionization source for the effective enrichment and rapid detection of phthalates in beverages

A novel, rapid, and simple detection method is proposed to realize the simultaneous detection of seven phthalate esters (PAEs) within 1.5 min. A suitable covalent organic framework (COF) was coated on a stainless steel substrate (COFCS) to serve as both an enrichment element and a solid substrate for electrospray ionization mass spectrometry (ESI-MS). Twenty microliters of elution solvent was added dropwise to the COFCS enriched with analytes, and then high voltage electricity was applied and combined with ambient mass spectrometry (AMS) to realize the detection of PAEs. In order to investigate the reliability of the COFCS-ESI-MS method, dimethyl phthalate (DMP), diethyl phthalate (DEP), ethyl phthalate (2-methoxy) (DMEP), phthalate(2-ethoxy) ethyl ester (DEEP), dipentyl phthalate (DPP), dihexyl phthalate (DHXP), and butyl benzyl phthalate (BBP) were detected simultaneously. The proposed method showed good linearity in the range 0.1-80 μg/L with the determination coefficient (R2) > 0.9916. The limits of detection (LODs) and limits of quantification (LOQs) of the determination technology were in the ranges 0.03-0.40 μg/L and 0.1-2.0 μg/L, respectively. The results demonstrated that the simultaneous detection of the seven PAEs in beverages can be realized using the method, and the spiked recoveries were in the range 85.17-104.09% with the relative standard deviations (RSDs) < 8.32%. In addition, the COFCS has good reusability and batch-to-batch repeatability and can be re-used at least 5 times and still maintain good enrichment performance.

Coupling microextraction techniques with substrate spray mass spectrometry, towards a faster analysis of biological samples

Direct coupling sample preparation with mass spectrometry has risen as a reliable analytical strategy in bioanalysis as it provides a high sample throughput. This approach avoids an exhaustive separation step, thus being cost-effective compared to the traditional analytical workflow. The selectivity and sensitivity levels rely on the mass spectrometric analysis and the appropriate selection of the sample preparation. Miniaturized extraction techniques have demonstrated particular utility in this coupling thanks to their ability to pre-concentrate the target analytes while removing many of the matrix components. This article reviews the main developments in combining microextraction techniques with mass spectrometry based on electrospray ionization, a consolidated ionization technique in bioanalysis. The article aims to provide an overview of the potential of these techniques by describing the most significant examples. The different approaches are classified according to the materials or devices used to perform the extraction and analysis.

In situ growth of hierarchical porous covalent organic framework coating for enhanced solid-phase microextraction of phenolic compounds

Covalent organic frameworks (COFs), when utilized as solid-phase microextraction (SPME) coating materials, exhibit remarkable abilities to concentrate phenols by thousands-fold owing to their vast surface area and exceptional stability. However, the prevalent micropores inherent in COFs can impede rapid mass transfer of target molecules, prolonging SPME extraction times. To addresses this limitation, this work introduces a novel approach by integrating hierarchical porous structures into COFs, leveraging polystyrene microspheres as hard templates during the in situ growth process of the SPME coating. Due to the presence of a hierarchical porous structure derived from the template, the resulting hierarchical porous TpBD coating, termed HP-TpBD, demonstrated enhanced extraction efficiency, accelerated extraction kinetics, and notably shortened extraction times for phenolic compounds. Coupled with gas chromatography-mass spectrometry, a highly sensitive method featuring a low limit of detection (0.20-0.28 ng L-1), a broad linear range (1.0∼1.0 × 104 ng L-1), and excellent precision (RSD < 8.5 %) was established. This methodology enables accurate quantitative analysis of phenols in water and soil samples. This work provides valuable insights into developing COF-based SPME coatings for the efficient extraction of volatile contaminants, paving the way for more efficient and sensitive analytical procedures.

A critical review of bioanalytical and clinical applications of solid phase microextraction

Studying the functions, mechanisms, and effects of drugs and other exogenous compounds on biological systems, together with investigations performed to understand biosystems better, comprises one of the most fascinating areas of research. Although classical sample preparation techniques are dominantly used to infer the relevant information from the investigated system, they fail to meet various imperative requirements, such as being environmentally friendly, applicable in-vivo, and compatible with online analysis. As a chameleon in the analytical toolbox, solid phase microextraction (SPME) is one of the best tools available for studying biological systems in unconventional ways. In this review, SPME is spotlighted, and its capability for bioanalytical applications, including drug analysis, untargeted and targeted metabolomics, in-vivo and clinical studies, is scrutinized based on studies reported in the past five years. In addition, novel extractive phases and instrumental coupling strategies developed to serve bioanalytical research are discussed to give the perspective for state-of-the-art and future developments. The literature assessment showed that SPME could act as a critical tool to investigate in-vivo biological systems and provide information about the elusive portion of the metabolome. Moreover, recently introduced miniaturized SPME probes further improved the low-invasive nature of the sampling and enabled sampling even from a single cell. The coupling of SPME directly to mass spectrometry significantly reduced the total analytical workflow and became one of the promising tools suitable for fast diagnostic purposes and drug analysis. The numerous applications and advancements reported in bioanalysis using SPME show that it will continue to be an indispensable technique in the future.

Advances in covalent organic frameworks for sample preparation

Sample preparation is crucial in analytical chemistry, impacting result accuracy, sensitivity, and reliability. Solid-phase separation media, especially adsorbents, are vital for preparing of liquid and gas samples, commonly analyzed by most analytical instruments. With the advancements in materials science, covalent organic frameworks (COFs) constructed through strong covalent bonds, have been increasingly employed in sample preparation in recent years. COFs have outstanding selectivity and/or excellent adsorption capacity for a single target or can selectively adsorb multiple targets from complex matrix, due to their large specific surface area, adjustable pore size, easy modification, and stable chemical properties. In this review, we summarize the classification of COFs, such as pristine COFs, COF composite particles, and COFs-based substrates. We aim to provide a comprehensive understanding of the different classifications of COFs in sample preparation within the last three years. The challenges and development trends of COFs in sample preparation are also presented.

Synthesis of a cysteine functional covalent organic framework via facile click reaction for the efficient solid phase extraction of substituted p-phenylenediamine-derived quinones

N,N'-Substituted p-phenylenediamine quinones (PPD-Qs) are the emerging toxicant, which transform from the rubber tire antioxidant N,N'-substituted p-phenylenediamines (PPDs). Because of their potential toxic and widespread occurrence in the environment, PPD-Qs have received great attention. However, efficiently extracting PPD-Qs from complex samples is still a challenge. Herein, a cysteine functional covalent organic framework (Cys-COF) designed according to the "donor-acceptor" sites of hydrogen bonding of PPD-Qs was synthesized via click reaction and then used as solid-phase extraction (SPE) adsorbent. Cys-COF can form the seven-member ring adsorption structure with PPD-Qs via hydrogen bonding. The adsorption mechanism was tentatively revealed by density functional theory (DFT). After optimizing the Cys-COF-SPE parameters, PPD-Qs were efficiently extracted from water, soil, sediment, and fish, followed by detection using ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The Cys-COF-SPE-UHPLC-MS/MS method exhibited ideal linearity (R2 ≥ 0.9932), high relative recoveries (80.4-111 %), and low limits of detection (0.0001-0.0013 ng mL-1). In addition, the bioconcentration kinetics in goldfish provides a feasible platform to investigate the toxicity and accumulated ability of PPD-Qs.

In situ fabrication of covalent organic frameworks on solid-phase microextraction probes coupled with electrospray ionization mass spectrometry for enrichment and determination of androgens in biosamples

Solid-phase microextraction (SPME) coupled with electrospray ionization mass spectrometry (ESI-MS) was developed for rapid and sensitive determination of endogenous androgens. The SPME probe is coated with covalent organic frameworks (COFs) synthesized by reacting 1,3,5-tri(4-aminophenyl)benzene (TPB) with 2,5-dioctyloxybenzaldehyde (C8PDA). This COFs-SPME probe offers several advantages, including enhanced extraction efficiency and stability. The analytical method exhibited wide linearity (0.1-100.0 µg L-1), low limits of detection (0.03-0.07 µg L-1), high enrichment factors (37-154), and satisfactory relative standard deviations (RSDs) for both within one probe (4.0-14.8%) and between different probes (3.4-12.7%). These remarkable performance characteristics highlight the reliability and precision of the COFs-SPME-ESI-MS method. The developed method was successfully applied to detect five kinds of endogenous androgens in female serum samples, indicating that the developed analytical method has great potential for application in preliminary clinical diagnosis.

Greenness assessment of microextraction techniques in therapeutic drug monitoring

Aim: In this study, we evaluated the greenness and whiteness scores for microextraction techniques used in therapeutic drug monitoring. Additionally, the cons and pros of each evaluated method and their impacts on the provided scores are also discussed. Materials & methods: The Analytical Greenness Sample Preparation metric tool and white analytical chemistry principles are used for related published works (2007-2023). Results & conclusion: This study provided valuable insights for developing methods based on microextraction techniques with a balance in greenness and whiteness areas. Some methods based on a specific technique recorded higher scores, making them suitable candidates as green analytical approaches, and some others achieved high scores both in green and white areas with a satisfactory balance between principles.

Recent progress of covalent organic frameworks as attractive materials for solid-phase microextraction: A review

Solid-phase microextraction (SPME) is a green, environmentally friendly, and efficient technique for sample pre-treatment. Covalent organic frameworks (COFs), a class of porous materials formed by covalent bonds, have gained prominence owing to their remarkable attributes, including large specific surface area, tunable pore size, and robust thermal/chemical stability. These characteristics have made COFs highly appealing as potential coatings for SPME fiber over the past decades. In this review, various methods used to prepare SPME coatings based on COFs are presented. These methods encompass physical adhesion, sol-gel processes, in situ growth, and chemical cross-linking strategies. In addition, the applications of COF-based SPME coating fibers for the preconcentration of various targets in environmental, food, and biological samples are summarized. Moreover, not only their advantages but also the challenges they pose in practical applications are highlighted. By shedding light on these aspects, this review aims to contribute to the continued development and utilization of COF materials in the field of sample pretreatment.