Direct analysis in real time-mass spectrometry for rapid quantification of five anti-arrhythmic drugs in human serum: application to therapeutic drug monitoring

Automatic MDSPE Combined with DART-HRMS for the Rapid Quantitation of 21 Synthetic Cathinones in Urine

A new, rapid, and automated method for the quantitation of 21 synthetic cathinones in urine was established using magnetic dispersive solid-phase extraction (MDSPE) in combination with direct analysis in real time-high-resolution mass spectrometry (DART-HRMS). Sample preparation and quantitation were verified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methcathinone-D3, α-PVP-D8, and proadifen (SKF525A) were used as internal standards. Magnetic HLB extractant and NaH2PO4/NaOH buffer (0.2 M, pH 7) were used in automatic MDSPE. All 21 synthetic cathinones could be detected and analyzed by DART-HRMS in under 1 min. It was proven that the linearities of 21 synthetic cathinones were suitable (R2 > 0.99) in the concentration ranges of 0.5-100 ng/mL or 1-100 ng/mL. The precision and accuracy values were all within ±15%, and the samples were stable under various conditions. The average time of each sample from preprocessing to completion of detection was approximately 2 min, allowing for rapid sample analysis. The relative error (RE) of the concentrations obtained by DART-HRMS and LC-MS/MS were within ±13.61%, and the linear coefficient (R) was 0.9964. The results of DART-HRMS and LC-MS/MS provided equivalent values at the 95% confidence level. In summary, a simple, fast, and convenient quantitation method via DART-HRMS was established. This application can be utilized to reduce backlogs and promote rapid case processing.

Advances in mass spectrometry-based multi-scale metabolomic methodologies and their applications in biological and clinical investigations

Metabolomics is a nascent field of inquiry that emerged in the late 20th century. It encompasses the comprehensive profiling of metabolites across a spectrum of organisms, ranging from bacteria and cells to tissues. The rapid evolution of analytical methods and data analysis has greatly accelerated progress in this dynamic discipline over recent decades. Sophisticated techniques such as liquid chromatograph mass spectrometry (MS), gas chromatograph MS, capillary electrophoresis MS, and nuclear magnetic resonance serve as the cornerstone of metabolomic analysis. Building upon these methods, a plethora of modifications and combinations have emerged to propel the advancement of metabolomics. Despite this progress, scrutinizing metabolism at the single-cell or single-organelle level remains an arduous task over the decades. Some of the most thrilling advancements, such as single-cell and single-organelle metabolic profiling techniques, offer profound insights into the intricate mechanisms within cells and organelles. This allows for a comprehensive study of metabolic heterogeneity and its pivotal role in multiple biological processes. The progress made in MS imaging has enabled high-resolution in situ metabolic profiling of tissue sections and even individual cells. Spatial reconstruction techniques enable the direct representation of metabolic distribution and alteration in three-dimensional space. The application of novel metabolomic techniques has led to significant breakthroughs in biological and clinical studies, including the discovery of novel metabolic pathways, determination of cell fate in differentiation, anti-aging intervention through modulating metabolism, metabolomics-based clinicopathologic analysis, and surgical decision-making based on on-site intraoperative metabolic analysis. This review presents a comprehensive overview of both conventional and innovative metabolomic techniques, highlighting their applications in groundbreaking biological and clinical studies.

Rapid quantification of phenobarbital and barbital in human whole blood by liquid-liquid extraction combined with DART-orbitrap-HRMS

PURPOSE

This study aims to develop and validate a rapid, simple, and efficient bioanalytical method for the simultaneous quantification of phenobarbital and barbital in human whole blood using liquid-liquid extraction combined with direct analysis in real time (DART) and high-resolution mass spectrometry (HRMS).

METHOD

Phenobarbital-d5 and aprobarbital were selected as internal standards (ISs) of phenobarbital and barbital, respectively. A mixed solvent of o-xylene and ethyl acetate at a ratio of 1:6 was used to extract analytes of interest and ISs from 100 μL of human whole blood samples. Phenobarbital and barbital were detected by DART-HRMS. The proposed method has been validated in accordance with United States Food and Drug Administration Guidelines for Bioanalytical Method Validation in terms of selectivity, linearity, accuracy, precision, matrix effect, recovery, stability, and dilution integrity.

RESULTS

The lower limits of quantification (LLOQs) of phenobarbital and barbital were both 10 ng/mL. The linearities were in the range of 10-1000 ng/mL (R² ≥ 0.99). The mean recovery values of phenobarbital and barbital were 99.7% and 88.1%, respectively. The interday and intraday precision values were less than 10.4%, and the interday and intraday accuracy values ranged from 87.6 to 106.7%. Furthermore, the validated method was applied to four cases of phenobarbital poisoning at the Shanghai Institute of Forensic Science.

CONCLUSION

The developed and fully validated method enabled the simultaneous quantification of phenobarbital and barbital in human whole blood and was successfully applied to authentic cases.

Plasma-based ambient mass spectrometry: Recent progress and applications

Ambient mass spectrometry (AMS) has grown as a group of advanced analytical techniques that allow for the direct sampling and ionization of the analytes in different statuses from their native environment without or with minimum sample pretreatments. As a significant category of AMS, plasma-based AMS has gained a lot of attention due to its features that allow rapid, real-time, high-throughput, in vivo, and in situ analysis in various fields, including bioanalysis, pharmaceuticals, forensics, food safety, and mass spectrometry imaging. Tens of new methods have been developed since the introduction of the first plasma-based AMS technique direct analysis in real-time. This review first provides a comprehensive overview of the established plasma-based AMS techniques from their ion source configurations, mechanisms, and developments. Then, the progress of the representative applications in various scientific fields in the past 4 years (January 2017 to January 2021) has been summarized. Finally, we discuss the current challenges and propose the future directions of plasma-based AMS from our perspective.

Ambient Ionization Mass Spectrometry: Application and Prospective

Mass spectrometry (MS) is a formidable analytical tool for the analysis of non-polar to polar compounds individually and/or from mixtures, providing information on the molecular weights and chemical structures of the analytes. During the last more than one-decade, ambient ionization mass spectrometry (AIMS) has developed quickly, producing a wide range of platforms and proving scientific improvements in a variety of domains, from biological imaging to quick quality control. These methods have made it possible to detect target analytes in real time without sample preparation in an open environment, and they can be connected to any MS system with an atmospheric pressure interface. They also have the ability to analyze explosives, illicit drugs, disease diagnostics, drugs in biological samples, adulterants in food and agricultural products, reaction progress, and environmental monitoring. The development of novel ambient ionization techniques, such as probe electrospray ionization, paper spray ionization, and fiber spray ionization, employed even at picolitre to femtolitre solution levels to provide femtogram to attogram levels of the target analytes. The special characteristic of this ambient ion source, which has been extensively used, is the noninvasive property of PESI of examination of biological real samples. The results in the current review supports the idea that AIMS has emerged as a pioneer in MS-based approaches and that methods will continue to be developed along with improvements to existing ones in the near future.

N-Heterocyclic Carbene Ligand Stability on Gold Nanoparticles in Biological Media

The ability to functionalize gold nanoparticle surfaces with target ligands is integral to developing effective nanosystems for biomedical applications, ranging from point-of-care diagnostic devices to site-specific cancer therapies. By forming strong covalent bonds with gold, thiol functionalities can easily link molecules of interest to nanoparticle surfaces. Unfortunately, thiols are inherently prone to oxidative degradation in many biologically relevant conditions, which limits their broader use as surface ligands in commercial assays. Recently, N-heterocyclic carbene (NHC) ligands emerged as a promising alternative to thiols since initial reports demonstrated their remarkable stability against ligand displacement and stronger metal-ligand bonds. This work explores the long-term stability of NHC-functionalized gold nanoparticles suspended in five common biological media: phosphate-buffered saline, tris-glycine potassium buffer, tris-glycine potassium magnesium buffer, cell culture media, and human serum. The NHCs on gold nanoparticles were probed with surface-enhanced Raman spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS). SERS is useful for monitoring the degradation of surface-bound species because the resulting vibrational modes are highly sensitive to changes in ligand adsorption. Our measurements indicate that imidazole-based NHCs remain stable on gold nanoparticles over the 21 days of examination in all tested environments, with no observed change in the molecule's SERS signature, XPS response, or UV-vis plasmon band.

Rapid quantitation of three synthetic cathinones in urine by magnetic dispersive solid-phase extraction combined with DART-HRMS

For the rapid quantitation of three synthetic cathinones, namely 1-(4-chlorophenyl)-2-(1-pyrrolidinyl)pentan-1-one (4-Cl-α-PVP), 1-(4-methylphenyl)-2-(methylamino)pentan-1-one (4-MPD), and 1-(5,6,7,8-tetrahydronaphthalen-2-yl)-2-(1-pyrrolidinyl)pentan-1-one (β-TH-naphyrone), in urine, a new method was established using magnetic dispersive solid-phase extraction (MDSPE) combined with direct analysis in real time and high-resolution mass spectrometry (DART-HRMS). Methcathinone-D3 and proadifen (SKF525A) were used as the internal standards. Hydrophobic magnetic adsorbents were used and consisted of hydrophobic functional group (divinylbenzene) and hydrophilic functional group (vinylpyrrolidone) at a ratio of 3 : 1, and NaH₂PO₄//NaOH buffer (0.2 M, pH 7) was used in MDSPE. Detection was conducted by DART-HRMS in less than 1 min. For 4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone, the limits of detection were 0.1 ng mL^-1, 0.05 ng mL^-1 and 0.1 ng mL^-1, and the linear ranges were 0.5-100 ng mL^-1, 0.2-100 ng mL^-1 and 0.2-100 ng mL^-1, respectively. The correlation coefficients were all greater than 0.99. The precision and deviation of accuracy were all within ±15%, and the stability of the samples was high under various conditions. The method was successfully applied to detect 4-Cl-α-PVP, 4-MPD and β-TH-naphyrone in rat urine after subcutaneous administration. In summary, a fast and convenient detection method was established, providing new and effective technical support for the rapid quantitation of three synthetic cathinones (4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone) for forensic purposes.

Bioanalytical strategies in drug discovery and development

A reliable, rapid, and effective bioanalytical method is essential for the determination of the pharmacokinetic, pharmacodynamic, and toxicokinetic parameters that inform the safety and efficacy profile of investigational drugs. The overall goal of bioanalytical method development is to elucidate the procedure and operating conditions under which a method can sufficiently extract, qualify, and/or quantify the analyte(s) of interest and/or their metabolites for the intended purpose. Given the difference in the physicochemical properties of small and large molecule drugs, different strategies need to be adopted for the development of an effective and efficient bioanalytical method. Herein, we provide an overview of different sample preparation strategies, analytical platforms, as well as procedures for achieving high throughput for bioanalysis of small and large molecule drugs.

Applications of ambient ionization mass spectrometry in 2020: An annual review

Recent developments in mass spectrometry (MS) analyses have seen a concerted effort to reduce the complexity of analytical workflows through the simplification (or removal) of sample preparation and the shortening of run-to-run analysis times. Ambient ionization mass spectrometry (AIMS) is an exemplar MS-based technology that has swiftly developed into a popular and powerful tool in analytical science. This increase in interest and demonstrable applications is down to its capacity to enable the rapid analysis of a diverse range of samples, typically in their native state or following a minimalistic sample preparation approach. The field of AIMS is constantly improving and expanding, with developments of powerful and novel techniques, improvements to existing instrumentation, and exciting new applications added with each year that passes. This annual review provides an overview of applications of AIMS techniques over the past year (2020), with a particular focus on the application of AIMS in a number of key fields of research including biomedical sciences, forensics and security, food sciences, the environment, and chemical synthesis. Novel ambient ionization techniques are introduced, including picolitre pressure-probe electrospray ionization and fiber spray ionization, in addition to modifications and improvements to existing techniques such as hand-held devices for ease of use, and USB-powered ion sources for on-site analysis. In all, the information provided in this review supports the view that AIMS has become a leading approach in MS-based analyses and that improvements to existing methods, alongside the development of novel approaches, will continue across the foreseeable future.