Review of online coupling of sample preparation techniques with liquid chromatography

An Update on Current Trend in Sample Preparation Automation in Bioanalysis: strategies, Challenges and Future Direction

Automation in sample preparation improves accuracy, productivity, and precision in bioanalysis. Moreover, it reduces resource consumption for repetitive procedures. Automated sample analysis allows uninterrupted handling of large volumes of biological samples originating from preclinical and clinical studies. Automation significantly helps in management of complex testing methods where generation of large volumes of data is required for process monitoring. Compared to traditional sample preparation processes, automated procedures reduce associated expenses and manual error, facilitate laboratory transfers, enhance data quality, and better protect the health of analysts. Automated sample preparation techniques based on robotics potentially increase the throughput of bioanalytical laboratories. Robotic liquid handler, an automated sample preparation system built on a robotic technique ensures optimal laboratory output while saving expensive solvents, manpower, and time. Nowadays, most of the traditional extraction processes are being automated using several formats of online techniques. This review covered most of the automated sample preparation techniques reported till date, which accelerated and simplified the sample preparation procedure for bioanalytical sample analysis. This article critically analyzed different developmental aspects of automated sample preparation techniques based on robotics as well as conventional sample preparation methods that are accelerated using automated technologies.

Internal multiple interactions-adsorption and external zwitterionic polymer-exclusion of restricted access materials as adsorbent for offline and online extraction of neonicotinoid pesticides in Goji samples

A method based on novel restricted access materials (RAMs) for the determination of neonicotinoid pesticides in Goji samples using offline and online solid phase extraction (SPE) coupled with high-performance liquid chromatography (LC). RAMs were synthesized using poly(chloromethylstyrene-co-divinylbenzene) (PVBC/DVB) microspheres as substrate, styrene (St) and n-vinylpyrrolidone (NVP) were first copolymerized on the interior to construct adsorption sites, and sulfobetaine methacrylate (SBMA) was then polymerized on the exterior to form exclusion sites via two-step surface initiated-atom transfer polymerization. The prepared PVBC/DVB@poly(St-co-NVP)@poly(SBMA) RAMs could efficiently extract neonicotinoid pesticides and automatically exclude proteins. Under the optimized conditions, the developed methods of offline (magnetic SPE and SPE column) and online extraction coupled with LC both using PVBC/DVB@poly(St-co-NVP)@poly(SBMA) RAMs as the extractant, exhibit a wide linearity, low limits of detection and limit of quantification and good inter-day and intra-day precision with satisfactory recoveries. Among these methods, online extraction coupled with LC based on novel RAMs exhibits clear advantages for the determination of neonicotinoid pesticides in Goji samples has clear advantages, such as simple operation by direct injection, short extraction times, and high accuracy with less human error.

Separation and purification of glycosides from medicinal plants based on strong polar separation medium with online closed-loop mode

Natural glycosides widely distributed in medicinal plants are valuable sources of therapeutic agents, showing various pharmacological effects. The separation and purification of natural glycosides are meaningful for their pharmacological research, which face with great challenges due to the complex of medicinal plants samples. In this work, two kinds of functional monolithic separation mediums A and S were fabricated and fully applied in the online extraction, separation and purification of active glycoside components from medicinal plants with a simple-procedure closed-loop mode. Chrysophanol glucoside and physcion glucoside were detected and separated from Rhei Radix et Rhizoma using separation medium A as a solid-phase extraction adsorbent. Rhapontin was isolated and purified from Rheum hotaoense C. Y. Cheng et Kao using separation medium S as the stationary phase of high-performance liquid chromatography. Compared to the reported literatures, high yield of 5.68, 1.20 and 4.76 mg g-1 of these three products were obtained with high purity. These two online closed-loop mode methods were carried out using high-performance liquid chromatography system, in which the sample injection, isolation and purification procedures are all online mode, and reduced loss compared to offline extraction and purification procedures, thus achieving high recovery and high purity.

Modern automated microextraction procedures for bioanalytical, environmental, and food analyses

Sample preparation frequently is considered the most critical stage of the analytical workflow. It affects the analytical throughput and costs; moreover, it is the primary source of error and possible sample contamination. To increase efficiency, productivity, and reliability, while minimizing costs and environmental impacts, miniaturization and automation of sample preparation are necessary. Nowadays, several types of liquid-phase and solid-phase microextractions are available, as well as different automatization strategies. Thus, this review summarizes recent developments in automated microextractions coupled with liquid chromatography, from 2016 to 2022. Therefore, outstanding technologies and their main outcomes, as well as miniaturization and automation of sample preparation, are critically analyzed. Focus is given to main microextraction automation strategies, such as flow techniques, robotic systems, and column-switching approaches, reviewing their applications to the determination of small organic molecules in biological, environmental, and food/beverage samples.

Recent Trends in Graphene-Based Sorbents for LC Analysis of Food and Environmental Water Samples

This review provides an overview of recent advancements in applying graphene-based materials as sorbents for liquid chromatography (LC) analysis. Graphene-based materials are promising for analytical chemistry, including applications as sorbents in liquid chromatography. These sorbents can be functionalized to produce unique extraction or stationary phases. Additionally, graphene-based sorbents can be supported in various materials and have consequently been applied to produce various devices for sample preparation. Graphene-based sorbents are employed in diverse applications, including food and environmental LC analysis. This review summarizes the application of graphene-based materials in food and environmental water analysis in the last five years (2019 to 2023). Offline and online sample preparation methods, such as dispersive solid phase microextraction, stir bar sorptive extraction, pipette tip solid phase extraction, in-tube solid-phase microextraction, and others, are reviewed. The review also summarizes the application of the columns produced with graphene-based materials in separating food and water components and contaminants. Graphene-based materials have been reported as stationary phases for LC columns. Graphene-based stationary phases have been reported in packed, monolithic, and open tubular columns and have been used in LC and capillary electrochromatography modes.

Online solid-phase extraction based on size-controllable spherical covalent organic framework for efficient determination of polybrominated diphenyl ethers in foods

An analytical method of microspheric brominated covalent organic framework (Br-COF)-online solid-phase extraction integrated with high-performance liquid chromatography (online SPE-HPLC) was proposed for efficiently enriching six polybrominated diphenyl ethers (PBDEs) in foods. The Br-COF microspheres were facilely prepared with uniformity and dispersion by a size-controllable synthesis at the room temperature. Attributed to multiple interactions of the halogen bonding, Van der Waals forces, hydrophobic interaction along with size-matching effect, Br-COF performed satisfactory extraction capacity for PBDEs compared with commercial adsorbents. Five primary influencing factors were optimized, including loading solvent, loading flow rate, elution solvent, elution flow rate and elution volume. Under the optimal parameters, the implement displayed excellent linear ranges (0.5-500 ng mL^-1) and low detection limits (0.01-0.05 ng mL^-1). The relative recoveries in six spiked food samples ranged from 87.8 to 119.7 % with relative standard deviations below 10 %. This research estabished a promising platform for quantitatively determining trace PBDEs in complex foods.

Bridging the gap: The critical role of laboratory developed tests in clinical toxicology

•Toxicology testing provides valuable information for patient management.•Current in vitro diagnostics (IVDs) are unable to meet all clinical needs.•Lab-developed tests (LDTs) in toxicology can be used to close clinical care gaps.•LDTs in clinical toxicology are almost exclusively mass spectrometry-based methods.

Online micro solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry for trace analysis of endogenous plant hormones in Ulva linza

OBJECTIVE

Ulva linza (L.) is a species of green algae widely distributed in China. We aimed to establish a sensitive online analytical method for quantification of endogenous phytohormones in fresh minute seaweed samples.

METHOD

The method for quantification of endogenous plant hormones in fresh minute samples was developed based on a homemade online micro solid phase extraction (m-SPE) system coupled with an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) platform. The online m-SPE instrument injected the eluent of m-SPE directly onto the LC separation column, improving the utilization of samples and saving time. The m-SPE column, of which the effective size was 9.6 × 2 mm i.d., was filled with 19 mg of C18 (10 μm).

RESULTS

Under optimized conditions, the limits of detection were 0.002-0.060 ng ml^-1 for five plant hormones. The actual sample recoveries of phytohormones were 76.4-103.4% and the coefficients of variance were below 14.1%. The temporal distribution of these endogenous plant hormones of U. linza during different growth periods is described.

CONCLUSION

The proposed online m-SPE method was successfully applied to quantification of endogenous acidic and alkaline plant hormones in U. linza. It provides important information for the further study of the physiological and ecological effects of plant hormones in lower algal species.

Fast and simplified quantitative multiresidue analytical method for pesticides in surface waters by UHPLC-MS/MS with online sample preparation

A quantitative multiresidue analytical method for the simultaneous analysis of current-use agricultural pesticides in surface waters is reported. The method involves minimal sample manipulation and small sample collection volumes (for 1 mL and 5 mL injections) with online sample clean-up and analyte preconcentration on a hydrophilic-lipophilic balance (HLB) column. To our knowledge, this online approach with the use of an HLB column has not yet been reported for multiresidue pesticide analysis in surface waters. Chromatographic separations of isomeric pesticides were achieved through the sequential coupling of C8 and polar endcapped C18 analytical columns. High resolution accurate mass (HRAM) quadrupole Orbitrap spectrometry was performed in full scan mode followed by data-dependent MS/MS fragmentation (FS-ddMS²) with concurrent electrospray ionization in both positive and negative modes. The method was validated for thirty-one (31) diverse current-use pesticides and demonstrated strong linearity (R² > 0.9912) and precision (% RSD <8.4%) with low quantitation limits (average LOQ of 41 ng L^-1). The majority of target analytes experienced minimal matrix effects (<±20%) in fortified environmental water samples. When applied to surface water samples, the method detected fourteen of the target analytes, including twelve herbicides, one insecticide, and one fungicide. This method offers a fast, simple, and reliable approach for the quantitative analysis of diverse current-use pesticides in surface water samples within hours of sample collection in the field. The robust nature of the method may allow for potential application to other types of water and the targeted or untargeted screening of other emerging contaminants.

Green Extraction Processes for Complex Samples from Vegetable Matrices Coupled with On-Line Detection System: A Critical Review

The detection of analytes in complex organic matrices requires a series of analytical steps to obtain a reliable analysis. Sample preparation can be the most time-consuming, prolonged, and error-prone step, reducing the reliability of the investigation. This review aims to discuss the advantages and limitations of extracting bioactive compounds, sample preparation techniques, automation, and coupling with on-line detection. This review also evaluates all publications on this topic through a longitudinal bibliometric analysis, applying statistical and mathematical methods to analyze the trends, perspectives, and hot topics of this research area. Furthermore, state-of-the-art green extraction techniques for complex samples from vegetable matrices coupled with analysis systems are presented. Among the extraction techniques for liquid samples, solid-phase extraction was the most common for combined systems in the scientific literature. In contrast, for on-line extraction systems applied for solid samples, supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, and pressurized liquid extraction were the most frequent green extraction techniques.

Microfluidic Paper-Based Analytical Devices for the Determination of Food Contaminants: Developments and Applications

Food safety is an issue that cannot be ignored at any time because of the great impact of food contaminants on people's daily life, social production, and the economy. Because of the extensive demand for high-quality food, it is necessary to develop rapid, reliable, and efficient devices for food contaminant detection. Microfluidic paper-based analytical devices (μPADs) have been applied in a variety of detection fields owing to the advantages of low-cost, ease of handling, and portability. This review systematically discusses the latest progress of μPADs, including the fundamentals of fabrication as well as applications in the detection of chemical and biological hazards in foods, hoping to provide suitable screening strategies for contaminants in foods and accelerating the technology transformation of μPADs from the lab into the field.

Solid-phase extraction techniques based on nanomaterials for mycotoxin analysis: An overview for food and agricultural products

Mycotoxin contamination is a globally concerned problem for food and agricultural products since it may directly or indirectly induce severe threats to human health. Sensitive and selective screening is an efficient strategy to prevent or reduce human and animal exposure to mycotoxins. However, enormous challenges exist in the determination of mycotoxins, arising from complex sample matrices, trace-level analytes, and the co-occurrence of diverse mycotoxins. Appropriate sample preparation is essential to isolate, purify, and enrich mycotoxins from complicated matrices, thus decreasing sample matrix effects and lowering detection limits. With the cross-disciplinary development, new solid-phase extraction strategies have been exploited and integrated with nanotechnology to meet the challenges of mycotoxin analysis. This review summarizes the advance and progress of solid-phase extraction techniques as the methodological solutions for mycotoxin analysis. Emphases are paid on nanomaterials fabricated as trapping media of SPE techniques, including carbonaceous nanoparticles, metal/metal oxide-based nanoparticles, and nanoporous materials. Advantages and limitations are discussed, along with the potential prospects. This article is protected by copyright. All rights reserved.

Recent Advances in Solid-Phase Extraction as a Platform for Sample Preparation in Biomarker Assay

Low levels of biomarkers and the complexity of bio sample make the analytical assay of several biomarkers a challenging issue. Suitable sample preparation run remain a vital part of the puzzle of diagnostic level. Enhancing the detection limit of bioanalytical methods start during the sample preparation procedure. A robust sample preparation method is needed to evaluate the number of biomarkers. As worldwide environmental issues attract expanding consideration, all the more harmless to the ecosystem investigations are liked. Solid-phase extraction (SPE) is an appealing strategy among the sample treatment methods due to the versatility of sorbent materials, less solvent consumption, and compatibility with analytical devices. Miniaturization of the SPE gives the chance to integrate the other analytical steps in a single run, known as an easy-to-use and effective method. SPE utilizes various SPE sorbent beds such as packed beads, porous polymer monoliths, molecularly imprinted polymers, membranes, or other magnetic form microstructures to achieve high surface-to-volume ratio and appropriate chemical properties effective extraction. Also, SPE is the methodology of interest to fulfill high recovery and efficiency demands. In this review, we intend to explain more recent methods for the rational design of SPE and miniaturized SPE to determine biomarkers from biological media. The headlines are subdivided into (1) packing materials in SPE, (2) setups for sample preparation by magnetic SPE, and (3) and future perspective for the application of SPE in sample preparation for analysis of biomarkers.

Online pressurized liquid extraction enables directly chemical analysis of herbal medicines: A mini review

Extraction is responsible for transferring components from solid materials into solvent. Tedious extraction procedures are usually involved in liquid chromatography-based chemical analysis of herbal medicines (HMs), resulting in extensive consumptions of organic solvents, time, energy, and materials, as well as the significant chemical degradation risks for those labile compounds. Fortunately, an emerging online pressurized liquid extraction (OLE, also known as online liquid extraction) technique has been developed for the achievement of directly chemical analysis for solid matrices in recent years, and in a short period, this versatile technique has been widely applied for the chemical analysis of HMs. In the present mini-review, we aim to briefly summarize the principles, the instrumentation, along with the application progress of this robust and flexible extraction technique in the latest six years, and the emerging challenges and future prospects are discussed as well. Special attention is paid onto the hyphenation of the versatile OLE module with LC-MS instrument. The described information is expected to introduce a promising OLE approach and to provide the guidance for the achievement of directly chemical analysis of, but not limited to, HMs.

Online Turbulent Flow Extraction and Column Switching for the Confirmatory Analysis of Stimulants in Urine by Liquid Chromatography-Mass Spectrometry

Stimulants are often used to treat attention deficit disorders and nasal congestion. As they can be misused and overdosed, the detection of stimulants is relevant in the toxicological field as well as in the doping control field. The effects of stimulants can indeed be beneficial for athletes. Therefore, their in-competition use is prohibited by the World Anti-Doping Agency (WADA). As stimulants represent one of the most detected categories of prohibited substances, automation of methods to detect and confirm their presence is desirable. Previous work has shown the advantages of using turbulent flow online solid-phase extraction liquid chromatography-tandem mass spectrometry (online SPE LC-MS-MS) for the detection and confirmation of diuretics and masking agents. Hence, a turbulent flow online SPE LC-MS-MS method, compliant with the WADA's identification criteria, was developed and validated for the detection and confirmation of 80 stimulants or metabolites with limits of identification varying between 10 (or possibly lower) and 100 ng/mL. As several metabolites are common metabolites for multiple administered stimulants, this means that with this method, misuse of well over 100 compounds can be detected. As the developed method uses the same columns and mobile phases as our turbulent flow online SPE LC-MS-MS method for the confirmation of diuretics and masking agents, there is no need to change the configuration of the instrument when switching between the diuretics method and the developed stimulants method.

Determination of Urinary Mycotoxin Biomarkers Using a Sensitive Online Solid Phase Extraction-UHPLC-MS/MS Method

In the course of assessing the human exposure to mycotoxins, biomarker-based approaches have proven to be important tools. Low concentration levels, complex matrix compositions, structurally diverse analytes, and the large size of sample cohorts are the main challenges of analytical procedures. For that reason, an online solid phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry (online SPE-UHPLC-MS/MS) method was developed, allowing for the sensitive, robust, and rapid analysis of 11 relevant mycotoxins and mycotoxin metabolites in human urine. The included spectrum of analytes comprises aflatoxin M₁ (AFM₁), altenuene (ALT), alternariol monomethyl ether (AME), alternariol (AOH), citrinin (CIT) and its metabolite dihydrocitrinone (DH-CIT), fumonisin B₁ (FB₁), ochratoxin A (OTA), and zearalenone (ZEN) as well as α- and β-zearalenol (α- and β-ZEL). Reliable quantitation was achieved by means of stable isotope dilution, except for ALT, AME and AOH using matrix calibrations. The evaluation of method performance displayed low limits of detection in the range of pg/mL urine, satisfactory apparent recovery rates as well as high accuracy and precision during intra- and interday repeatability. Within the analysis of Zimbabwean urine samples (n = 50), the applicability of the newly developed method was shown. In addition to FB₁ being quantifiable in all analyzed samples, six other mycotoxin biomarkers were detected. Compared to the occurrence rates obtained after analyzing the same sample set using an established dilute and shoot (DaS) approach, a considerably higher number of positive samples was observed when applying the online SPE method. Owing to the increased sensitivity, less need of sample handling, and low time effort, the herein presented online SPE approach provides a valuable contribution to human biomonitoring of mycotoxin exposure.

Ultrasensitive determination of serotonin in human urine by a two dimensional capillary isotachophoresis-capillary zone electrophoresis hyphenated with tandem mass spectrometry

A two-dimensional capillary isotachophoresis-capillary zone electrophoresis method hyphenated with tandem mass spectrometry was developed and validated for ultrasensitive quantification of serotonin in real human urine samples. Under optimal conditions, the separation was achieved within 12 min (including on-line sample preparation) with the limit of detection of 34 pg mL^-1 (due to a large volume sample injection, here 10 µL, and isotachophoretic preconcentration). This concentration limit represents the lowest value for serotonin in comparison to other previously published separation methods employing mass spectrometry detection and applied to urine matrices. Thanks to high orthogonality, on-line concentration and clean-up effects of this approach, other excellent validation parameters such as linearity (coefficient of determination > 0.99), inter-day and intra-day precision (relative standard deviations 3.5-12.2%), accuracy (relative errors within 99-109.4%), and recovery (96-102%) could be easily obtained too. To demonstrate applicability of the method, we monitored serotonin levels in various real samples (from a healthy volunteer and clinical ones). The determined levels, normalized on the creatinine concentrations, were in the range of 6.81-12.86 ng mmol^-1 creatinine This advanced method is suggested for an effective, reliable, high sample throughput, and low cost routine clinical screening or targeted metabolomic studies of serotonin in urine samples.

A review of micro-solid-phase extraction techniques and devices applied in sample pretreatment coupled with chromatographic analysis

Sample pretreatment is one of the most crucial and error-prone steps of an analytical procedure; it consents to improve selectivity and sensitivity by sample clean-up and pre-concentration. Nowadays, the arousing interest in greener and sustainable analytical chemistry has increased the development of microextraction techniques as alternative sample preparation procedures. In this review, we aimed to show two different categorizations of the most used micro-solid-phase extraction (μSPE) techniques. In essence, the first one concerns the solid-phase extraction (SPE) sorbent selection and structure: normal-phase, reversed-phase, ion-exchange, mixed-mode, molecular imprinted polymer, and special techniques (e.g., doped cartridges for specific analytes). The second is a grouping of the commercially available μSPE products in categories and sub-categories. We present every device and technology into the classifications paying attention to their historical development and the actual state of the art. So, this study aims to provide the state-of-the-art of μSPE techniques, highlighting their advantages, disadvantages, and possible future developments in sample pretreatment.

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

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

Automated sample preparation for the detection and confirmation of hypoxia-inducible factor stabilizers in urine

As hypoxia-inducible factor stabilizers (HIFs) can artificially enhance an athlete's erythropoiesis, the World Anti-Doping Agency prohibits their use at all times. Every urine sample for doping control analysis has to be evaluated for the presence of HIFs and therefore sensitive methods that allow high sample throughput are needed. Samples suspicious for the presence of HIFs need to be confirmed following the identification criteria established by the World Anti-Doping Agency. Previous work has shown the advantages of using turbulent flow online solid-phase extraction (SPE) procedures to reduce matrix effects and retention time shifts. Furthermore, the use of online SPE allows for automation and high sample throughput. Both an initial testing procedure (ITP) and a confirmation method were developed and validated, using online SPE liquid chromatography-tandem mass spectrometry (LC-MS/MS), with limits of detection between 0.1 ng/ml (or possibly lower) and 4 ng/ml (or higher for GSK360a) and limits of identification between 0.1 ng/ml (or possibly lower) and 1.17 ng/ml. The ITP only takes 6.5 min per sample. To the best of our knowledge, these are the first ITP and confirmation methods that include more than three HIFs without the need for manual sample preparation.

Recent advances on functional nucleic acid-based biosensors for detection of food contaminants

It has seen increasing development of reliable, robust, and flexible biosensors for rapid food-safety analysis in the past few decades. Recently, functional nucleic acid-based biosensors have attracted attention because of their programmability, bottom-up characteristics, and structural switches. However, few systematic reviews devoted to categorizing the potential of DNA nanostructures and devices were found for detecting food contaminants. Hence, the applications of functional nucleic acid-based biosensors were reviewed for analyzing food contaminants, including foodborne pathogen bacteria, biotoxins, heavy metals, and et al. In addition to categorizing the various biosensors, multiple signal readout strategies, such as optical, electrochemical, and mass-based signals were also examined. Finally, the future changes and potential opportunities, as well as practical applications of functional nucleic acid-based biosensors were discussed.

Integration of Solid-Phase Extraction and Reversed-Phase Chromatography in Single Protein-Coated Columns for Direct Injection of Bupivacaine in Human Serum

A rapid, reliable and precise integrated solid-phase extraction (SPE) and reversed-phase liquid chromatography method was developed and validated to determine bupivacaine in human serum using single protein-coated analytical columns. The protein-coated columns were packed with four different sorbents: TSK-ODS, LiChrosorb RP-8, LiChrosorb RP-2 and μ-Bondapak CN-bonded silica. The method involved direct injection of serum sample onto the columns for trapping of the analyte, clean-up from weakly retained serum endogenous components, as well as the final separation. The protein-coated columns operated in two different chromatographic modes. Serum proteins were extracted and cleaned up by SPE, whereas the final separation of bupivacaine was based on reversed-phase chromatography. The protein-coated TSK-ODS column resulted in more accurate peak integration and more reproducible results. A linear relationship between the concentrations of drug and peak areas was confirmed in the range of 100-2000 ng/mL. Detection and quantification limits were 24.85 and 85.36 ng/mL, respectively. The average recovery for bupivacaine ranged from 96.48% to 98.81%. The present methodology was successfully applied, with a high degree of confidence, to analyze clinical samples obtained from patient receiving 0.5% bupivacaine therapy.

Amino-modified Scholl-coupling mesoporous polymer for online solid-phase extraction of plant growth regulators from bean sprouts

A new amino-modified Scholl-coupling mesoporous polymer (NH₂@SMPA)-online solid-phase extraction method, coupled with high-performance liquid chromatography (online SPE-HPLC) was established for the analysis of six plant growth regulators (PGRs) in bean sprouts. NH₂@SMPA was synthesized by acid-catalyzed deacetylation of acetylamino-Scholl-coupling mesoporous polymer (SMPA). The diversity of functional groups, such as aromatic, acetylamino, and NH₂, was conducive to multiple binding interactions between NH₂@SMPA and PGRs. NH₂@SMPA exhibited superior extraction capability for PGRs, compared with SMPA and commercial adsorbents. The extraction conditions, including loading solvent, pH of loading solution, eluting solvent, and flow rates of loading and elution, were optimized. Under the optimized conditions, wide linear ranges (0.01-500 μg kg^-1) and low detection limits (2.34-20.2 ng kg^-1) were obtained. The recoveries were satisfactory, i.e., 86.0% to 109% with relative standard deviations ≤9.8% (n = 3). Finally, the online SPE-HPLC method was successfully used for determination of PGRs in bean sprouts.

An automatic online solid-phase dehydrate extraction-ultra-high performance supercritical fluid chromatography-tandem mass spectrometry system using a dilution strategy for the screening of doping agents in human urine

An automatic online solid-phase dehydrate extraction (SPDE)-ultra-high performance supercritical fluid chromatography (UHPSFC)-MS/MS system was developed in this study, in which the automatic SPDE procedure was coupled with UHPSFC to allow UHPSFC to analyze aqueous samples directly. Moreover, a pre-column dilution strategy was employed, which focused the analytes in strong desorption solvent on the column head and helped to obtain narrow and symmetric peaks. The online SPDE-UHPSFC-MS/MS system was firstly applied to the screening of 45 prohibited substances in human urine for doping control, during which all the mechanisms and features of the online system were fully studied. The majority (91%) of the target compounds achieved weak matrix effects (80-120%), indicating that the online method was accurate and reliable thanks to the SPDE procedure and efficient UHPSFC separation. Owing to the reduction of the matrix effects, large volume injection and the pre-column dilution, the online system could achieve high sensitivity with the LODs ranging from 0.0380 ng L^-1 to 1.24 μg L^-1. Under the optimized conditions, the extraction recoveries of 66% target analytes were more than 50%. All the target compounds showed good linearity with linear correlation coefficients higher than 0.9928. The accuracy values of all the spiked prohibited substances were within 80.8-119.7%, while the RSDs% for the intra-/inter-day precision were within 10.8% and 15.4%. Compared with the dilute-and-shoot-ultra-high performance liquid chromatography-MS/MS method, in which the urine samples were simply diluted before analyzing, this online method was superior in sensitivity and reducing matrix effects, which demonstrated its utility in doping control. Compared with the previously reported online SPE-SFC system, the online SPDE-UHPSFC-MS/MS system showed advantages in automation, efficiency, sensitivity and chromatographic performance. In summary, the online SPDE-UHPSFC-MS/MS system is capable of analyzing complex aqueous samples.

Investigating Monoliths (Vinyl Azlactone-co-Ethylene Dimethacrylate) as a Support for Enzymes and Drugs, for Proteomics and Drug-Target Studies

Prior to mass spectrometry, on-line sample preparation can be beneficial to reduce manual steps, increase speed, and enable analysis of limited sample amounts. For example, bottom-up proteomics sample preparation and analysis can be accelerated by digesting proteins to peptides in an on-line enzyme reactor. We here focus on low-backpressure 100 μm inner diameter (ID) × 160 mm, 180 μm ID × 110 mm or 250 μm ID × 140 mm vinyl azlactone-co-ethylene dimethacrylate [poly(VDM-co-EDMA)] monoliths as supports for immobilizing of additional molecules (i.e., proteases or drugs), as the monolith was expected to have few unspecific interactions. For on-line protein digestion, monolith supports immobilized with trypsin enzyme were found to be suited, featuring the expected characteristics of the material, i.e., low backpressure and low carry-over. Serving as a functionalized sample loop, the monolith units were very simple to connect on-line with liquid chromatography. However, for on-line target deconvolution, the monolithic support immobilized with a Wnt pathway inhibitor was associated with numerous secondary interactions when exploring the possibility of selectively trapping target proteins by drug-target interactions. Our initial observations suggest that (poly(VDM-co-EDMA)) monoliths are promising for e.g., on-line bottom-up proteomics, but not a "fit-for-all" material. We also discuss issues related to the repeatability of monolith-preparations.

Ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) in practice: analysis of drugs and pharmaceutical formulations

Background

UHPLC-MS/MS is connected in various research facilities for the qualitative and quantitative investigation of a pharmaceutical substance, pharmaceutical items, and biological specimen.

Main body

The commence review article is an endeavor to offer pervasive awareness around assorted aspects and details about the UHPLC-MS/MS and related techniques with the aim on practice to an estimation of medicinal active agents in the last 10 years. The article also focused on isolation, separation, and characterization of present impurity in drug and biological samples.

Conclusion

Review article compiles a general overview of medicinally important drugs and their analysis with UHPLC-MS/MS. It gives fundamental thought regarding applications of UHPLC-MS/MS for the study on safety limit. The summary of developed UHPLC-MS/MS methods gives a contribution to the future trend and limitations in this area of research.

Dynamic extraction coupled on-line to liquid chromatography with a parallel sampling interface-a proof of concept for monitoring extraction kinetics

On-line hyphenation of extraction with chromatography has been explored in several different types of combinations. However, monitoring the complete process of a dynamic, continuous-flow extraction is not possible with any hyphenated system reported so far. The current work demonstrates that this challenging task can be effectively fulfilled by using a parallel sampling interface, which mimics the concept of comprehensive two-dimensional chromatography. In this study, pressurised hot water extraction was coupled on-line with ultra-high-performance liquid chromatography. The set-up was utilised in a kinetic study of dynamic pressurised hot water extraction of curcuminoids from turmeric powder. Compound-specific extraction curves were obtained, which clearly indicated the rate-limiting factors of the extraction processes under different conditions. Additionally, thermal degradation of curcumin during the extraction could also be demonstrated in some of the extractions.

An online field-assisted micro-solid-phase extraction device coupled with high-performance liquid chromatography for the direct analysis of solid samples

Herein, a total online device based on field-assisted extraction (FAE), micro-solid-phase extraction (μ-SPE), and high-performance liquid chromatography (HPLC) was designed. Solid samples were pretreated with ultrasound-microwave synergic effects, and then the extract was cleaned up online with a monolithic column, followed by HPLC analysis. The cross-actions between ultrasound and microwave along with other extraction parameters were studied systematically. The efficiency of this online method was verified in the determination of polycyclic aromatic hydrocarbons (PAHs) in foods and tetracycline antibiotics (TCAs) in cosmetic samples. The detection limits of nine PAHs including fluorene, phenanthrene, anthracene, fluoranthene, benzo[k]fluoranthene, benz[a]anthracene, benzo[b]fluoranthene, pyrene, and benzo[a]pyrene were all within 0.075-0.30 μg/kg, as well as four TCAs including oxytetracycline, tetracycline, chlortetracycline, and doxycycline were within 0.02-0.06 μg/kg. Six PAHs were found in roast potatoes and baked fish and the recoveries were in the range of 71.5-119.7% with RSDs of 0.2-10.9% (n = 3). The recoveries for TCAs in cosmetic samples were in the range of 75.3-118.0% with RSDs lower than 8.2% (n = 3). Compared with those offline methods, this total online FAE-μ-SPE-HPLC method not only simplifies the operation process, but also increases the precision and accuracy. Beyond trace analytes analysis in solid and semi-solid matrixes, application of this total online analysis method can also be extended to investigate field-assisted extraction mechanisms. Graphical abstract.

A novel aptamer-based online magnetic solid phase extraction method for simultaneous determination of urinary 8-hydroxy-2'-deoxyguanosine and monohydroxylated polycyclic aromatic hydrocarbons

In this work, an innovative aptamer-based magnetic adsorbent (Fe₃O₄@PDA-aptamer MNPs) was prepared by hydrothermal synthesis method followed by the surface functionalization of nanoparticles. After fixing in a steel stainless tube as sorbent of magnetic solid phase extraction (MSPE), an online magnetic solid phase extraction-high performance liquid chromatography-mass spectrometry (online-MSPE-HPLC-MS) method was developed and applied for the determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) simultaneously in urine. The synthesized sorbent presented outstanding features, including large specific surface area, high enrichment capacity and excellent stability. High throughput analysis can be achieved by affinity-specific adsorption of 8-OHdG and non-specific adsorption of OH-PAHs at the same time. In addition, online MSPE can greatly simplify the analysis process, reduce human errors and enhance the sensitivity. When compared with offline MSPE, a sensitivity enhancement of 30-400 times was obtained for the online method. Some experimental parameters such as the amount of the sorbent, sampling flow rate and sample volume, were optimized systematically. Under the optimal conditions, the limits of detection (LOD) were in the range of 0.028-0.114 ng mL^-1, and the correlation coefficients (R²) were higher than 0.9962. The relative standard deviations (RSDs) were less than 16.1% (n = 5) and the recoveries ranged from 71% to 116%. The above results show that the rapid, sensitive and automated online-MSPE-HPLC-MS method has potential application in the simultaneous determination of 8-OHdG and PAHs in complex sample matrix to assess the environmental exposure level.