Recent advances in sample preparation techniques for quantitative detection of pharmaceuticals in biological samples

Liquid-liquid and solid-liquid extractions with low-temperature partitioning - A review

The paper represents the first review of solvent extraction techniques utilizing the low-temperature partitioning/purification (LTP) approach. Initially conceived in the 1960s to purify extracts from fatty matrices, it wasn't until the 2000s that this approach received increasing attention for its efficacy in extracting organic compounds from diverse samples, often without additional cleanup steps. This review covers a brief history and proposes a mechanism for LTP-based solvent extraction. Furthermore, the principal practical issues of the technique are spotlighted, elucidating the factors influencing extraction efficiency. The advantages, limitations, and potential combinations with other extraction techniques of the LTP-based solvent extractions are analyzed. The versatility of the LTP approach is demonstrated by its applications in extracting various compounds from food, environmental, and biological samples, emphasizing its potential for rapid sample preparation with minimal steps, few chemicals, and minimal analyst intervention.

Quick and high-throughput quantification of β-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg using dispersive solid phase extraction

A reliable liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry (LC-Q-Orbitrap HRMS) method was developed for the simultaneous identification and quantification of 13 β-agonist residues in bovine liver, meat, milk, kidney, poultry, and egg. Dispersive-solid phase extraction (d-SPE) using acetonitrile (ACN) was used to prepare the samples. The analyte in the extracts was separated on a reversed-phase Accucore aQ (50 mm × 2.1 mm, 2.6 μm) using a mobile phase of an aqueous solution containing 2 mM ammonium acetate and acetonitrile (ACN) 0.1 % formic acid. The method was validated in accordance with Commission Implementing Regulation (CIR) EU 2021/808 at six different concentrations ranging from 0.1 to 5 μg/kg. The mean recoveries ranged from 65 to 94 %, while repeatability and reproducibility values were all below 13 %. The linearity, as correlation coefficients (R2) ranged from 0.9955 to 0.9999. The decision limit (CCα) and detection capability (CCβ) ranges were 0.11-0.13 µg/kg and 0.12-0.15 µg/kg, respectively. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.004-0.048 μg/kg and 0.010-0.075 μg/kg, respectively. Of the 180 samples that were collected from local markets in Egypt, 21.11 % had β-agonist residues. The mean concentration (µg/kg) and detection frequency (%) of the most frequently found β-agonist in the samples were as follows: terbutaline (2.63 µg/kg and 90 %), ractopamine (5.14 µg/kg and 23.3 %). The method's applicability was verified by successfully completing two rounds of proficiency testing (PT).

Hyphenation of microflow chromatography with electrospray ionization mass spectrometry for bioanalytical applications focusing on low molecular weight compounds: A tutorial review

Benefits of miniaturized chromatography with various detection modes, such as increased sensitivity, chromatographic efficiency, and speed, were recognized nearly 50 years ago. Over the past two decades, this approach has experienced rapid growth, driven by the emergence of mass spectrometry applications serving -omics sciences and the need for analyzing minute volumes of precious samples with ever higher sensitivity. While nanoscale liquid chromatography (flow rates <1 μL/min) has gained widespread recognition in proteomics, the adoption of microscale setups (flow rates ranging from 1 to 100 μL/min) for low molecular weight compound applications, including metabolomics, has been surprisingly slow, despite the inherent advantages of the approach. Highly heterogeneous matrices and chemical structures accompanied by a relative lack of options for both selective sample preparation and user-friendly equipment are usually reported as major hindrances. To facilitate the wider implementation of microscale analyses, we present here a comprehensive tutorial encompassing important theoretical and practical considerations. We provide fundamental principles in micro-chromatography and guide the reader through the main elements of a microflow workflow, from LC pumps to ionization devices. Finally, based on both our literature overview and experience, illustrated by some in-house data, we highlight the critical importance of the ionization source design and its careful optimization to achieve significant sensitivity improvement.

Harnessing Bioluminescent Bacteria to Develop an Enzymatic-free Enzyme-linked immunosorbent assay for the Detection of Clinically Relevant Biomarkers

Enzyme-linked immunosorbent assay (ELISA) is the gold standard technique for measuring protein biomarkers due to its high sensitivity, specificity, and throughput. Despite its success, continuous advancements in ELISA and immunoassay formats are crucial to meet evolving global challenges and to address new analytical needs in diverse applications. To expand the capabilities and applications of immunoassays, we introduce a novel ELISA-like assay that we call Bioluminescent-bacteria-linked immunosorbent assay (BBLISA). BBLISA is an enzyme-free assay that utilizes the inner filter effect between the bioluminescent bacteriaAllivibrio fischeriand metallic nanoparticles (gold nanoparticles and gold iridium oxide nanoflowers) as molecular absorbers. Functionalizing these nanoparticles with antibodies induces their accumulation in wells upon binding to molecular targets, forming the classical immune-sandwich complex. Thanks to their ability to adsorb the light emitted by the bacteria, the nanoparticles can suppress the bioluminescence signal, allowing the rapid quantification of the target. To demonstrate the bioanalytical properties of the novel immunoassay platform, as a proof of principle, we detected two clinically relevant biomarkers (human immunoglobulin G and SARS-CoV-2 nucleoprotein) in human serum, achieving the same sensitivity and precision as the classic ELISA. We believe that BBLISA can be a promising alternative to the standard ELISA techniques, offering potential advancements in biomarker detection and analysis by combining nanomaterials with a low-cost, portable bioluminescent platform.

Treating Alzheimer's disease using nanoparticle-mediated drug delivery strategies/systems

The administration of promising medications for the treatment of neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) is significantly hampered by the blood-brain barrier (BBB). Nanotechnology has recently come to light as a viable strategy for overcoming this obstacle and improving drug delivery to the brain. With a focus on current developments and prospects, this review article examines the use of nanoparticles to overcome the BBB constraints to improve drug therapy for AD The potential for several nanoparticle-based approaches, such as those utilizing lipid-based, polymeric, and inorganic nanoparticles, to enhance drug transport across the BBB are highlighted. To shed insight on their involvement in aiding effective drug transport to the brain, methods of nanoparticle-mediated drug delivery, such as surface modifications, functionalization, and particular targeting ligands, are also investigated. The article also discusses the most recent findings on innovative medication formulations encapsulated within nanoparticles and the therapeutic effects they have shown in both preclinical and clinical testing. This sector has difficulties and restrictions, such as the need for increased safety, scalability, and translation to clinical applications. However, the major emphasis of this review aims to provide insight and contribute to the knowledge of how nanotechnology can potentially revolutionize the worldwide treatment of NDDs, particularly AD, to enhance clinical outcomes.

A new approach towards highly sensitive detection of endogenous N-acetylaspartic acid, N-acetylglutamic acid, and N-acetylaspartylglutamic acid in brain tissues based on strong anion exchange monolith microextraction coupled with UHPLC-MS/MS

A novel in-tube solid-phase microextraction coupled with an ultra-high performance liquid chromatography-mass spectrometry method has been established for simultaneous quantification of three crucial brain biomarkers N-acetylaspartic acid (NAA), N-acetylglutamic acid (NAG), and N-acetylaspartylglutamic acid (NAAG). A polymer monolith with quaternary ammonium as the functional group was designed and exhibited efficient enrichment of target analytes through strong anion exchange interaction. Under the optimized conditions, the proposed method displayed wide linear ranges (0.1-80 nM for NAA and NAG, 0.2-160 nM for NAAG) with good precision (RSDs were lower than 15%) and low limits of detection (0.019-0.052 nM), which is by far the most sensitive approach for NAA, NAG, and NAAG determination. Furthermore, this approach has been applied to measure the target analytes in mouse brain samples, and endogenous NAA, NAG, and NAAG were successfully detected and quantified from only around 5 mg of cerebral cortex, cerebellum, and hippocampus. Compared with existing methods, the newly developed method in the current study provides highest sensitivity and lowest sample consumption for NAA, NAG, and NAAG measurements, which would potentially be utilized in determining and tracking these meaningful brain biomarkers in diseases or treatment processes, benefiting the investigations of pathophysiology and treatment of brain disorders.

Selective Extraction and Quantification of Hemoglobin Based on a Novel Molecularly Imprinted Nanopolymeric Structure of Poly(acrylamide-vinyl imidazole)

Imbalances in hemoglobin (Hb) levels can lead to conditions such as anemia or polycythemia, emphasizing the importance of precise Hb extraction from blood. To address this, a novel synthetic imprinted polymer was meticulously developed for capturing and separating Hb. Poly(acrylamide-vinylimidazole) nanopolymer (poly(AAm-VIM)) was synthesized using acrylamide and vinyl imidazole as functional monomers through surfactant-free emulsion polymerization. Characterization using FTIR, particle size, zeta potential, and SEM ensured the polymer's structure. The Hb-imprinted nanopolymer (Hb-poly(AAm-VIM)) demonstrated notable specificity, with a calculated Hb-specific adsorption value (Qmax) of 3.7377 mg/g in a medium containing 2.5 mg/mL Hb. The molecularly imprinted polymer (MIP) exhibited approximately 5 times higher Hb adsorption than the nonimprinted polymer (NIP). Under the same conditions, the imprinted nanopolymer displayed 2.39 and 2.17 times greater selectivity for Hb over competing proteins such as bovine serum albumin (BSA) and lysozyme (Lys), respectively. Also, SDS-PAGE analysis results confirmed the purification of Hb by the molecularly imprinted nanopolymer. These results underscore the heightened specificity and efficacy of the molecularly imprinted nanopolymer in selectively targeting Hb atoms among other proteins. Incorporating such polymers is justified by their notable affinity, cost-effectiveness, and facile production. This research contributes valuable insights into optimizing synthetic imprinted polymers for efficient Hb extraction, with potential in medical diagnostics and treatment applications.

Pretreatment and analysis techniques development of TKIs in biological samples for pharmacokinetic studies and therapeutic drug monitoring

Tyrosine kinase inhibitors (TKIs) have emerged as the first-line small molecule drugs in many cancer therapies, exerting their effects by impeding aberrant cell growth and proliferation through the modulation of tyrosine kinase-mediated signaling pathways. However, there exists a substantial inter-individual variability in the concentrations of certain TKIs and their metabolites, which may render patients with compromised immune function susceptible to diverse infections despite receiving theoretically efficacious anticancer treatments, alongside other potential side effects or adverse reactions. Therefore, an urgent need exists for an up-to-date review concerning the biological matrices relevant to bioanalysis and the sampling methods, clinical pharmacokinetics, and therapeutic drug monitoring of different TKIs. This paper provides a comprehensive overview of the advancements in pretreatment methods, such as protein precipitation (PPT), liquid-liquid extraction (LLE), solid-phase extraction (SPE), micro-SPE (μ-SPE), magnetic SPE (MSPE), and vortex-assisted dispersive SPE (VA-DSPE) achieved since 2017. It also highlights the latest analysis techniques such as newly developed high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) methods, capillary electrophoresis (CE), gas chromatography (GC), supercritical fluid chromatography (SFC) procedures, surface plasmon resonance (SPR) assays as well as novel nanoprobes-based biosensing techniques. In addition, a comparison is made between the advantages and disadvantages of different approaches while presenting critical challenges and prospects in pharmacokinetic studies and therapeutic drug monitoring.

Enhancing the water-resistance of MOF-199 film through incorporation of microporous organic networks for solid-phase microextraction of BTEX in aqueous environments with improved efficiency

BACKGROUND

The practical application of moisture sensitive metal organic frameworks (MOFs) in extraction technology faces challenges related to competitive adsorption and water stability. The target analytes cannot be effectively extracted under humid conditions due to the competitive moisture adsorption and/or framework structure collapse of MOFs. In this study, the microporous organic networks (MONs) were synthesized through Sonogashira coupling reaction to use for hydrophobic modification on the surface of MOF-199.

RESULTS

The MOF-199@MON as coating was deposited on stainless steel wires for solid-phase microextraction (SPME) of benzene series (BTEX) in aqueous environments. Under the optimal extraction conditions, the MOF-199@MON coated fiber for SPME coupled with GC-MS for the determination of BTEX gave the linear range of 0.5-500 μg L-1, the limit of detections (LODs, S/N = 3) of 0.01-0.04 μg L-1, the limit of quantifications (LOQs, S/N = 10) of 0.04-0.12 μg L-1, the enhancement factors of 3567-4878, and the intra-day, inter-day and fiber-to-fiber precisions (relative standard deviations, RSDs) of 1.0-9.8, 1.9-7.9 and 4.5-9.5 %, respectively. The developed method was successfully applied to the analysis of BTEX in water samples with the recoveries of 71.0 %-113 %.

SIGNIFICANCE

This work reveals the home-made SPME fibers have a long service life (the extraction efficiency of fiber decreased by only 7.26 %-13.14 % after 100 cycles). The potential of MON functionalized MOFs as effective adsorbents for the SPME of pollutants in the water environment.

Preparation and evaluation of a tryptophan based hypercrosslinked porous polymer as an efficient adsorbent for pipette tip solid-phase extraction of sulfonamides

A novel tryptophan-based porous polymer is designed and synthesized via a facile one-step hypercrosslinking polymerization process, and applied as sorbent for extraction of trace sulfonamides in foodstuffs. The developed polymer has high surface area, large conjugate system, and abundant functional groups (e.g., π-π stacking, hydrogen bonding, hydrophobic and electrostatic attraction interactions), which endow it with superior affinity and high adsorption capacity for sulfonamides (16.16-59.29 mg g-1). The optimized SPE method is coupled with HPLC-DAD to create a sensitive and efficient protocol that provides good linearity (R2 ≥ 0.9979), low limits of detection, satisfactory recoveries (92.5-109.5 %) and high precisions (RSDs < 8.24). In addition, the newly proposed method greatly reduces the amount of adsorbent (2.0 mg) and organic solvent (2.0 mL) used. Adsorption kinetics, isotherms, and simulation calculations studies further reveal the presence of monolayer adsorption, chemical adsorption process, and multiple interactions. Thus, this work presents a polymer capable of multiple interactions for the pretreatment of trace sulfonamides in foodstuffs.

Layer-by-layer assembly of PDDA/MWCNTs thin films as an efficient strategy for extraction of organic compounds from complex samples

This article presents the assembly and characterization of poly(diallyldimethylammonium chloride)/multi-walled carbon nanotubes (PDDA/MWCNTs) thin films on borosilicate bottles using a layer-by-layer (LBL) approach. The thin films, consisting of 10 bilayers of coating materials, were thoroughly characterized using UV-VIS spectroscopy, scanning electron microscopy (SEM), and zeta potential measurements. The modified bottles were then utilized for the extraction of analytes with diverse acid-base characteristics, including drugs, illicit drugs, and pesticides, from saliva, urine, and surface water samples. The studied analytes can be adsorbed on the surface of the LBL film mainly through hydrogen bonding and/or hydrophobic interactions. Remarkably high extraction percentages of up to 92 % were achieved, accompanied by an impressive enhancement in the analytical signal of up to 12 times when the sample volume was increased from 0.7 to 10 mL. These results highlight the outstanding extraction and sorption capabilities of the developed material. Additionally, the (PDDA/MWCNTs)10 films exhibited notable resistance to extraction and desorption processes, enabling their reuse for at least 5 cycles. The straightforward and cost-effective fabrication of these sorbent materials using the LBL technique, combined with the ability to extract target compounds during sample transportation and/or storage, renders this sample preparation method a promising alternative.

Single substrate-functionalized molybdenum oxide nanozyme for specific colorimetric monitoring of xanthine oxidase activity

Xanthine-functionalized molybdenum oxide nanodots (X-MoO3-x NDs) with peroxidase (POD)-like activity were developed for selective, sensitive, and facile colorimetric quantification of xanthine oxidase (XO). Xanthine functionalization can not only be favorable for the successful nanozyme preparation, but also for the specific recognition of XO as well as the simultaneous generation of hydrogen peroxide, which was subsequently transformed into hydroxyl radical to oxidize the chromogenic reagent based on the POD-like catalysis. Under the optimized conditions, the colorimetric biosensing platform was established for XO assay without addition of further substrates, showing good linearity relationship between absorbance difference (ΔA) and XO concentrations in the range 0.05-0.5 U/mL (R2 = 0.998) with a limit of detection (LOD) of 0.019 U/mL. The quantification of XO occurs in 25 min, which is superior to the previously reported and commercial XO assays. The proposed method has been successfully used in the assay of human serum samples, showing its high potential in the field of clinical monitoring.

Microextraction based on liquid-solid phase transition of benzoic acid: Extraction of statins from human urine followed by chromatographic analysis

Herein, a microextraction method was reported based on the liquid-solid phase transition of benzoic acid to quantify two statins, namely lovastatin and simvastatin in authentic human urine. The principle of the method is based on the phase transition of benzoic acid by altering the pH of the sample solution enabling efficient dispersion and phase separation in one step. Due to the moderate melting point of benzoic acid, its solidification is performed at ambient temperature without the need for sample cooling. Various experimental parameters that affect the performance of the analytes (i.e. extractant type and its concentration, acid type and concentration, and sample volume) have been examined and optimized. The method was validated based on the total error concept. For this purpose, accuracy profiles were constructed in the concentration range of 100-5000 ng mL-1 while β-expectation tolerance intervals fell within ±15% demonstrating that 95% of future results will not exceed the defined bias limits. The intra-day and inter-day method precision was less than 4.7% and 4.3% for both analytes, while the limit of detection was 15 ng mL-1 for both analytes. It was also proved that the usage of benzoic acid is advantageous in minimizing the potential inter-conversion of the analytes during the acidification step of the extraction procedure. The green potential of the proposed analytical scheme was examined based on Green Analytical Procedure index. The proposed sample pretreatment technique proved to be a valuable tool offering selectivity and rapidness. The developed method was used for the analysis of real human urine obtained after the administration of statin-based pharmaceutical formulations.

A C4-modified bipyridinium multi-mode stationary phase for reversed phase, hydrophilic interaction and ion exchange chromatography

A novel C4-modified bipyridinium stationary phase (Sil-DPC4) was prepared and characterized by elemental analysis (EA) and Fourier transform infrared spectrometry (FT-IR) and further investigated for multi-mode liquid chromatography. The chromatographic performances of Sil-DPC4 were evaluated by reversed-phase chromatography using polycyclic aromatic hydrocarbons (PAHs), phenylamines and phenols, hydrophilic interaction chromatography using nucleosides and nucleobases, and ion exchange chromatography using inorganic ions and organic ions. The effects of the acetonitrile content, salt concentration and pH value of the mobile phase on the retention of Sil-DPC4 were also investigated. Sil-DPC4 showed multiple retention mechanisms including π-π, hydrophobic and electrostatic interactions for PAHs, phenylamines and phenols compared with a dipyridine modified silica stationary phase (Sil-DP) and C18 in RPLC, faster separation for nucleosides and nucleobases compared with Sil-DP, and higher hydrophilicity than HILIC in HILIC, and stronger retention and better separation ability for inorganic ions and organic ions in comparison to Sil-DP in IEC. Besides, Sil-DPC4 was used successfully to detect iodide in artificial seawater and had the potential to analyze radionuclide iodine-131 in seawater. In conclusion, multiple retention mechanisms of Sil-DPC4 could make it have potential applications in complex samples.

Advanced porous organic materials for sample preparation in pharmaceutical analysis

The development of novel sample preparation media plays a crucial role in pharmaceutical analysis. To facilitate the extraction and enrichment of pharmaceutical molecules in complex samples, various functionalized materials have been developed and prepared as adsorbents. Recently, some functionalized porous organic materials have become adsorbents for pharmaceutical analysis due to their unique properties of adsorption and recognition. These advanced porous organic materials, combined with consequent analytical techniques, have been successfully used for pharmaceutical analysis in complex samples such as environmental and biological samples. This review encapsulates the progress of advanced porous materials for pharmaceutical analysis including pesticides, antibiotics, chiral drugs, and other compounds in the past decade. In addition, we also address the limitations and future trends of these porous organic materials in pharmaceutical analysis.

Simultaneous biomonitoring of volatile organic compounds' metabolites in human urine samples using a novel in-syringe based fast urinary metabolites extraction (FaUMEx) technique coupled with UHPLC-MS/MS analysis

Assessing the impact of human exposure to environmental toxicants is often crucial to biomonitoring the exposed dose. In this work, we report a novel fast urinary metabolites extraction (FaUMEx) technique coupled with UHPLC-MS/MS analysis for the highly sensitive and simultaneous biomonitoring of the five major urinary metabolites (thiodiglycolic acid, s-phenylmercapturic acid, t,t-muconic acid, mandelic acid, and phenyl glyoxylic acid) of common volatile organic compounds' (VOCs) exposure (vinyl chloride, benzene, styrene, and ethylbenzene) in human. FaUMEx technique comprises of two-steps, liquid-liquid microextraction was performed first in an extraction syringe using 1 mL of methanol (pH 3) as an extraction solvent and then, the extractant was passed through a clean-up syringe (pre-packed-with various sorbents including 500 mg anhydrous MgSO₄, 50 mg C18, and 50 mg SiO₂) to obtain the high order of matrice clean-up and preconcentration efficiency. The developed method displayed excellent linearity, and the correlation coefficients were >0.998 for all the target metabolites with detection and quantification limits of 0.02-0.24 ng mL^-1 and 0.05-0.72 ng mL^-1, respectively. Furthermore, the matrix effects were < ±5%, and inter and intra-day precision were <9%. Moreover, the presented method was applied and validated to real sample analysis for biomonitoring of VOC's exposure levels. The results showed that the developed FaUMEx-UHPLC-MS/MS method is fast, simple, low-cost, low-solvent consumption, high sensitivity with good accuracy and precision for five targeted urinary VOCs' metabolites. Therefore, the presented dual-syringe mode FaUMEx strategy with UHPLC-MS/MS technique can be applied to biomonitoring of various urinary metabolites to assess human exposure to environmental toxicants.

Quick and high-throughput quantification of 22 β-agonists residues in animal-derived foods using enzymatic probe sonication

A high demand exists in veterinary drug residual analysis for rapid, automatic and high-throughput analytical techniques that produce data simultaneous and faster. Here, we describe a combined automated solid-phase extraction (SPE) and enzymatic probe sonication (EPS), subsequently ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the quick extraction, automated clean-up as well as simultaneous quantification of 22 β-agonists residues in animal-derived foods. Enhanced by the ultrasonic probe, only 2 min was needed for exhaustively extraction of β-agonists from foods of animal-origin; whereas traditional enzymatic digestion methods require hours or even days, which making it more appropriate for high-throughput biomonitoring. Moreover, the clean-up and pre-concentration procedures were conducted on the automatic SPE, which allowed 36 samples being performed simultaneously within 30 min. The method was successfully applied for analyzing 56 animal-derived food samples, 53.6 % of which contained detectable levels of at least one kind of β-agonists. Interestingly, both the detection rate and residual level of β-agonists in the ruminants (bovine and sheep) were higher as compared with the swine. Concerning the real food samples analyzed, the findings of this study suggest that stricter measures should be adopted to control the illegal usage of β-agonists on the farm animals, particularly for the ruminants.

Synthesis and evaluation of ginsenosides imprinted polymer-based chromatographic stationary phase

The molecular imprinting technique has aroused great interest in preparing novel stationary phases, and the resulting materials named molecularly imprinted polymers coated silica packing materials exhibit good performance in separating diverse analytes based on their good characteristics (including high selectivity, simple synthesis, and good chemical stability). To date, mono-template is commonly used in synthesizing molecularly imprinted polymers-based stationary phases. The resulting materials always own the disadvantages of low column efficiency and restricted analytes, and the price of ginsenosides with high purity was very high. In this study, to overcome the weaknesses of molecularly imprinted polymers-based stationary phases mentioned above, the multi-templates (total saponins of folium ginseng) strategy was used to prepare ginsenosides imprinted polymer-based stationary phase. The resulting ginsenosides imprinted polymer-coated silica stationary phase has a good spherical shape and suitable pore structures. Additionally, the total saponins of folium ginseng were cheaper than other kinds of ginsenosides. Moreover, the ginsenosides imprinted polymer-coated silica stationary phase-packed column performed well in the separation of ginsenosides, nucleosides, and sulfonamides. The ginsenosides imprinted polymer-coated silica stationary phase possesses good reproducibility, repeatability, and stability for seven days. Therefore, a multi-templates strategy for synthesizing the ginsenosides imprinted polymer-coated silica stationary phase is considered in the future.

The development of microfluidic-based western blotting: Technical advances and future perspectives

Over the past two decades significant technical advancement in the field of western blotting has been made possible through the utilization of microfluidic technologies. In this review we provide a critical overview of these advancements, highlighting the advantages and disadvantages of each approach. Particular attention is paid to the development of now commercially available systems, including those for single cell analysis. This review also discusses more recent developments, including algorithms for automation and/or improved quantitation, the utilization of different materials/chemistries, use of projection electrophoresis, and the development of triBlots. Finally, the review includes commentary on future advances in the field based on current developments, and the potential of these systems for use as point-of-care devices in healthcare.

Deep eutectic solvent-based dispersive liquid-liquid microextraction followed by smartphone digital image colorimetry for the determination of carbofuran in water samples

A detection method of carbofuran (CBF) in water samples was reported using deep eutectic solvent (DES)-based dispersive liquid-liquid microextraction (DLLME) combined with digital image colorimetry (DIC), which was environmentally friendly, solvent-saving, rapid, and convenient. Under alkaline conditions, the green and multifunctional extractant DESs dissociated into linalool and heptanoic acid, and CBF was hydrolyzed to 2,3-dihydro-2,2-dimethyl-7-benzofuranol and further coupled with fast blue BB salt to form an azo derivative. Heptanoic acid led to the dispersion of linalool to extract the orange-red azo derivative; DIC was used for quantitative analysis using a smartphone with its associated ease of data-acquisition. This experiment optimized the types, molar ratios, and volumes of DESs and the amounts of sodium carbonate and sodium chloride. Under optimal conditions, the limits of detection (LOD) and quantitation (LOQ) were 0.024-0.032 mg L^-1 and 0.081-0.108 mg L^-1, respectively. The extraction recoveries in real samples (tap, pond, and river water) were 92.4-101.0% with a relative standard deviation below 4.6%. This method has successfully analyzed CBF in different water samples and shows prospects for the monitoring and control of CBF residues in other environmental samples.

Homemade Pipette Tip Solid-Phase Extraction for the Simultaneous Determination of 40 Drugs of Abuse in Urine by Liquid Chromatography–Tandem Mass Spectrometry

Pipette tip solid-phase extraction facilitates the handling of low-volume samples and organic solvents in order to achieve more environmentally friendly pre-treatment sample techniques. The use of pipette tip extraction was examined for the quick and simple determination of a heterogeneous group of 40 drugs of abuse and some of their metabolites in urine by liquid chromatography coupled to tandem mass spectrometry. Several parameters were studied and optimized, including those which can affect extraction efficiencies, such as the amount of sorbent and the volumes and number of aspirating/dispensing cycles of the sample and organic solvents. The linear range of this method was between the quantification limit and 75 or 100 ng mL−1. Detection limits between 0.025 and 0.500 ng mL−1 and quantification limits from 0.100 to 1.500 ng mL−1 were achieved, which are adequate to determine the studied compounds in urine from drug users. Finally, in order to prove its suitability in toxicological and forensic analyses, the method was successfully applied to 22 urine specimens from women who were starting a detoxification program. Cocaine was the most frequently detected substance, as its presence or the presence of its main metabolite was found in 86% of the analyzed samples.

Salt-Induced Homogeneous Liquid–Liquid Microextraction of Piroxicam and Meloxicam from Human Urine Prior to Their Determination by HPLC-DAD

A salt-induced homogeneous liquid–liquid microextraction (SI-HLLME) protocol combined with high-performance liquid chromatography–diode array detection is presented for the first time for the determination of piroxicam and meloxicam in human urine. The main parameters affecting the performance of the sample preparation protocol were optimized by means of a two-step experimental design (i.e., 2-level fractional factorial design and Box–Behnken design). Following its optimization, the proposed method was thoroughly validated in terms of the total error concept in order to take into consideration the random and systematic errors. For the target analytes, accuracy profiles were constructed, and they were used as graphical decision-making tools. In all cases, the β-expectation tolerance intervals complied with the acceptance criteria of ±15%, proving that 95% of future results will fall within the defined bias limits. The limits of detection were 0.02 μg mL−1 and 0.03 μg mL−1 for piroxicam and meloxicam, respectively. The relative standard deviations were lower than 4.4% in all cases, and the mean relative biases ranged between −5.7 and 3.4% for both drugs. The proposed scheme is simple and rapid, while it is characterized by high sample throughput. Moreover, SI-HLLME requires reduced sample and reagent consumption, according to the requirements of Green Analytical Chemistry.

A novel 3D printed device with conductive elements for electromembrane extraction combined with HPLC and UV detector

This paper is focused on proposing for a new design and setup for electromembrane extraction. A new cap was designed and conductive vials of different shape were fabricated using three-dimensional printing. The new cap holds three fibers to enhance electromembrane extraction recovery. Conductive vials can simultaneously perform as electrodes therefore, there is no need to include an electrode in sample solutions. Phenobarbital and phenytoin were used as model compounds to assess the setup performance. Under optimal conditions, these analytes were extracted from the sample solution at pH = 9 to the acceptor solution at pH = 13 with a voltage of 40 V for 20 min, while 1-octanol was employed as the supported-liquid-membrane. The influence of conductive vials geometry on the recovery was examined and effects of different shapes were studied by performing numerical simulation to establish electric potential distribution. Of the vials tested with circular, triangular and floral-like cross-sections the latter exhibited the best voltage distribution. The circular vial had the highest recovery attributed to its better hydrodynamic shape, which allows rapid fluid sample transport and therefore enhanced system recovery. The extraction recovery and RSD of circular vial with three fibers was 33.0 and 7.6 for phenobarbital and 42.2 and 10.4 for phenytoin. This article is protected by copyright. All rights reserved.

Generic Enrichment of Organic Contaminants in Human Biomonitoring: Application in Monitoring Early Life Exposures to Fipronil via Breast Milk

In human biomonitoring, a high-throughput extraction and enrichment method for multiple types of organic contaminants at the part-per-trillion level is critical yet challenging, especially in the limited sample volume. When large-scale sample analysis is involved, low cost is often what we should consider. We describe a generic and straightforward cold-induced liquid-liquid extraction (CI-LLE) strategy to meet this need. Current methods for extracting and enriching organic contaminants from biological samples often require multistep sample processing, including specially tailoring the extraction solvent or adsorbents. This method uses cold-induced phase separation to achieve the extraction and enrichment of studied organic contaminants by adjusting the proportion of acetonitrile/water mixture, so as to integrate the extraction and enrichment in one step without additional reagents and adsorbents. In this study, fipronil insecticide was used as a representative compound to determine the key parameters of CI-LLE. The optimized CI-LLE procedure allowed simultaneous extraction and enrichment of studied organic contaminants, providing excellent enrichment factors (especially for lipophilic organic contaminants). CI-LLE was further applied in monitoring early life exposures of fipronil in 109 breast milk samples. This study provided baseline data on fipronil levels in breast milk samples from China. For infants, exposure to fipronil is of concern. In summary, CI-LLE provides a feasible solution for a generic, efficient, and low-cost preparation of biological samples and promotes high-throughput batch analysis of organic contaminants for large-scale human biomonitoring.

Current development of bioanalytical sample preparation techniques in pharmaceuticals

Sample preparation is considered as the bottleneck step in bioanalysis because each biological matrix has its own unique challenges and complexity. Competent sample preparation to extract the desired analytes and remove redundant components is a crucial step in each bioanalytical approach. The matrix effect is a key hurdle in bioanalytical sample preparation, which has gained extensive consideration. Novel sample preparation techniques have advantages over classical techniques in terms of accuracy, automation, ease of sample preparation, storage, and shipment and have become increasingly popular over the past decade. Our objective is to provide a broad outline of current developments in various bioanalytical sample preparation techniques in chromatographic and spectroscopic examinations. In addition, how these techniques have gained considerable attention over the past decade in bioanalytical research is mentioned with preferred examples. Modern trends in bioanalytical sample preparation techniques, including sorbent-based microextraction techniques, are primarily emphasized.

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Bioanalytical sampling techniques are described with suitable applications in pharmaceuticals.

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The pros and cons of each bioanalytical sampling techniques are described.

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Relevant biological matrices are outlined.

PDMS-coated γCD-MOF solid-phase microextraction fiber for BTEX analysis with boosted performances

Owing to the ubiquitous occurrence and chemotoxicity of BTEX (benzene, toluene, ethylbenzene and xylene), the development of stable and accurate analysis methods that can assess environment risks and can generate monitoring data rapidly is urgent. In this work, a new strategy was proposed for efficient detection of BTEX. By creatively utilizing thermal deposition method, a robust SPME fiber was fabricated, where the γCD-MOF acted as the adsorbent, while PDMS functionalized as the adhesive and protective coating. Benefiting from the protection of PDMS, the γCD-MOF fiber presented significantly better extraction performance and exhibited long-term structural stabilities in aqueous or methanol samples up to a week. The stable and improved properties of γCD-MOF demonstrated that the PDMS protected the MOF components from the adverse effects of solvent. The detection limits of PDMS modified γCD-MOF fiber for BTEX was as low as 0.13-0.29 ng L^-1 that accompanied with wide linear range of 1-1000 ng L^-1, which was significantly superior to commercial PDMS fiber and other MOF-based fibers. Besides, the feasibility of the proposed method was verified by the quantitative determination of BTEX in real water samples. This work presents an effective strategy for creating ultrasensitive and stable SPME fibers based on γCD-MOF for applications in aqueous samples or other poor solvent.

Effect of sample matrices on supported liquid membrane: Efficient electromembrane extraction of cathinones from biological samples

In this work, the effect of sample matrix on electromembrane extraction (EME) was investigated for the first time using cathinones (log P < 1.0) as polar basic model analytes. Ten supported liquid membranes (SLMs) were tested for EME from spiked buffer solutions, urine, and whole blood samples, respectively. For buffer solutions, SLMs containing aromatic solvents provided higher EME recovery than non-aromatic solvents, which confirmed the significance of cation-π interactions for EME of basic substances. Interestingly, when applied to urine and whole blood samples, aromatic SLMs were less efficient, while non-aromatic SLMs containing abundant hydrogen-bond acidity/basicity were efficient. These observations were explained by SLM fouling, and the antifouling property of the SLM was clearly dependent on the nature of the SLM solvent. Accordingly, a binary SLM containing aromatic 1-ethyl-2-nitrobenzene (ENB) and non-aromatic 1-undecanol (1:1 v/v) was developed. This binary SLM was not prone to fouling, and provided high recoveries of cathinones from urine and whole blood. EME based on this SLM was optimized and evaluated in combination with liquid chromatography tandem mass spectrometry (LC-MS/MS), and the linear ranges with R² ≥ 0.9903 for cathinones in whole blood and urine were 5-200 ng/mL and 1-200 ng/mL, respectively. The LOD and LOQ of cathinones were ranged from 0.12 to 0.54 ng/mL and 0.38-1.78 ng/mL, respectively. The repeatability and accuracy bias at three levels were ≤11% and within 10%, respectively. In addition, the matrix effect ranged from 88% to 118% was also in compliance with guidelines for bioanalytical method validation provided by the European Medicines Agency.