Matrix-Compatible Solid-Phase Microextraction Pin Coupled Directly to Mass Spectrometry using Probe Electrospray Ionization

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

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

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

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

Sensitive fluorescence detection based on dimeric G-quadruplex combined with enzyme-assisted solid-phase microextraction of streptomycin in honey

Streptomycin (STR), an aminoglycoside antibiotic with the potential to persist in honey and other food products, may induce allergy, toxicity and antibiotic resistance in humans. In this study, we developed a solid-phase microextraction (SPME) biosensor based on a quartz rod that was modified with double-stranded DNA structures consisting of partially complementary G-rich base DNA strand and STR aptamer. The STR isolated by SPME initially bound to the aptamer. Then the remaining double-stranded DNA structures were cleaved by the Nt.BstNBI enzyme, resulting in release of G-quadruplex dimers. The latter formed a complex with thioflain T fluorescent dye, resulting in an amplified fluorescence response. The method exhibited high sensitivity (a limit of detection of 10.84 pM), wide linear range (0.05 nM ∼ 500 nM (with determination coefficient > 0.99)), and simple operation, making it suitable and convenient for STR detection. Successful STR determination in genuine honey samples was demonstrated.

Embedding Mixed Sorbents in Binder: Solid-Phase Microextraction Coating with Wide Extraction Coverage and Its Application in Environmental Water Analysis

Solid-phase microextraction (SPME) is a simple and highly effective sample-preparation technique for water analysis. However, the extraction coverage of a given SPME device with a specific coating can be an issue when analyzing multiple environmental contaminants. Therefore, instead of synthesizing one sorbent material with dual or multiple functions, we investigated a new strategy of preparing SPME blades using a homogeneous slurry made by mixing three different sorbent particles─namely, hydrophobic/lipophilic balanced (HLB), HLB-weak cationic exchange (HLB-WCX), and HLB-weak anionic exchange (HLB-WAX)─with a polyacrylonitrile (PAN) binder. The developed coating is matrix compatible, as the binder functions not only as a glue for immobilizing the sorbent particles but also as a porous filter, which only allows small molecules to enter the pores and interact with the particles, thus avoiding contamination from large elements. The results confirmed that the proposed mixed-coating SPME device provides good extraction performance for polar and nonpolar as well as positively and negatively charged compounds. Based on this device, three comprehensive analytical methodologies─high-throughput SPME-LC-MS/MS (for the quantitative analysis of targeted drugs of abuse and artificial sweeteners), in-bottle SPME-LC-high resolution MS (HRMS) (for the untargeted screening of organic contaminants), and on-site drone sampling SPME-LC-HRMS (for on-site sampling and untargeted screening)─were developed for use in environmental water analysis. The resultant data confirm that the proposed strategies enable comprehensive water quality assessment by using a single SPME device.