Contributions of theory to method development in solid-phase extraction

Dilute-and-shoot approach for the high-throughput LC-MS/MS determination of illicit drugs in the field of wastewater-based epidemiology

The determination of illicit drugs in urban influent wastewater (IWW) enables the monitoring of spatial and temporal drug usage trends and assessment of community lifestyle habits. The increasing number of wastewater surveillance studies has emphasized the necessity for the development of rapid, high-throughput methods that maintain high quality data. This work evaluates the use of a dilute-and-shoot methodology, based on direct injection (DI) of centrifuged samples, as an alternative approach to the widely applied sample pre-treatment based on solid-phase extraction, for the liquid chromatography-tandem mass spectrometry determination of seven widely consumed illicit drugs and their metabolites in IWW (amphetamine; cocaine metabolite, benzoylecgonine; ketamine; 3,4-methylenedioxymethamphetamine (MDMA); methamphetamine; cannabis metabolite, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THCCOOH); heroin metabolite, 6-acetylmorphine (6-MAM)). Comparison of both approaches in terms of matrix effects, sensitivity and accuracy, demonstrates the DI method suitability to correctly quantify these analytes in IWW, with a limit of quantification lower than 30 ng L-1 for most compounds. After validation of the method and participation in an interlaboratory exercise, the DI method was applied to the analysis of 54 IWW samples collected from different Spanish wastewater treatment plants. Additionally, quality controls were incorporated in each analysis batch to support the DI method applicability and robustness. The use of a 10 μL-DI reduces time-consuming sample preparation, analysis time and measurement uncertainty. Moreover, it supports green chemistry by reducing the consumption of organic solvents and it facilitates logistics by collecting, transporting, and storing less sample volume. The methodology is therefore especially appropriate for monitoring illicit drugs in large wastewater-based epidemiology sampling campaigns or when fast near real-time results are needed.

Restricted double access ionic imprinted polymer for online extraction and determination of copper from milk samples via FIA-FAAS system

BACKGROUND

Determining metals in complex biological samples, such as milk, typically involves dry or wet decomposition. However, these techniques have limitations, including low selectivity, risk of contamination, and the use of large reagent volumes. To solve these problems, solid-phase extraction (SPE) using multifunctional sorbents has been extensively explored. In this context, this work proposed synthesizing a new restricted double access ionic imprinted polymer (RAIIP-BSA), for online SPE and determination of Cu2+ from untreated milk samples via flow injection analysis and flame atomic absorption spectrometry (FIA-FASS).

RESULTS

Firstly, the polymer was obtained by bulk polymerization using Cu2+ as a template, 4-vinyl pyridine as a functional monomer, and glycidyl methacrylate as a hydrophilic comonomer. Subsequently, it was covered with bovine serum albumin, creating the restricted double access barrier. The obtained material could exclude 97 % of the proteins from milk samples. RAIIP-BSA was chemically and physically characterized. The main extraction variables were optimized via multivariate optimization. The method showed good figures of merit, such as linearity ranging from 0.05 to 1.0 mg L-1, LoD and LoQ of 0.03 and 0.05 mg L-1, intra- and interday precision ranging from 0.73 to 4.14 % and 0.16-3.68 %, and an intra- and interday accuracy ranging from 97.0 to 115.0 % and 103.0-119.0 %, respectively.

SIGNIFICANCE

The developed method demonstrates the effective extraction of Cu2+ from untreated milk samples, exhibiting selectivity, high extraction capacity, prolonged sorbent (RAIIP-BSA) durability, simplicity, and swift operation. This method holds promise as an alternative to conventional metal analysis approaches in complex matrices.

Biopolymers as a Potential Alternative for the Retention of Pollutants from Vinasse: An In Silico Approach

Vinasse, a waste from the bioethanol industry, presents a crucial environmental challenge due to its high organic matter content, which is difficult to biodegrade. Currently, no sustainable alternatives are available for treating the amount of vinasse generated. Conversely, biopolymers such as cellulose, carboxymethylcellulose, and chitosan are emerging as an interesting alternative for vinasse control due to their flocculating capacity against several organic compounds. This study seeks to determine the thermodynamic behavior of in silico interactions among three biopolymers (cellulose, carboxymethylcellulose, and chitosan) regarding 15 organic compounds found in vinasse. For this, the Particle Mesh Ewald (PME) method was used in association with the Verlet cutoff scheme, wherein the Gibbs free energy (ΔG) was calculated over a 50 ns simulation period. The findings revealed that cellulose showed a strong affinity for flavonoids like cyanidin, with a maximum free energy of -84 kJ/mol and a minimum of -55 kJ/mol observed with phenolic acids and other flavonoids. In contrast, chitosan displayed the highest interactions with phenolic acids, such as gallic acid, reaching -590 kJ/mol. However, with 3-methoxy-4-hydroxyphenyl glycol (MHPG), it reached an energy of -70 kJ/mol. The interaction energy for flavonoid ranged from -105 to -96 kJ/mol. Finally, carboxymethylcellulose (CMC) demonstrated an interaction energy with isoquercetin of -238 kJ/mol, while interactions with other flavonoids were almost negligible. Alternatively, CMC exhibited an interaction energy of -124 kJ/mol with MHPG, while it was less favorable with other phenolic acids with minimal interactions. These results suggest that there are favorable interactions for the interfacial sorption of vinasse contaminants onto biopolymers, indicating their potential for use in the removal of contaminants from the effluents of the bioethanol industry.

Selectivity evaluation of extraction systems

Extraction is the most common sample preparation technique prior to chromatographic analysis for samples which are too complex, too dilute, or contain matrix components incompatible with the further use of the separation system or interfere in the detection step. The most important extraction techniques are biphasic systems involving the transfer of target compounds from the sample to a different phase ideally accompanied by no more than a tolerable burden of co-extracted matrix compounds. The solvation parameter model affords a general framework to characterize biphasic extraction systems in terms of their relative capability for solute-phase intermolecular interactions (dispersion, dipole-type, hydrogen bonding) and within phase solvent-solvent interactions for cavity formation (cohesion). The approach is general and allows the comparison of liquid and solid extraction phases using the same terms and is used to explain the features important for the selective enrichment of target compounds by a specific extraction phase using solvent extraction, liquid-liquid extraction, and solid-phase extraction for samples in a gas, liquid, or solid phase. Hierarchical cluster analysis with the system constants of the solvation parameter model as variables facilitates the selection of solvents for extraction, the identification of liquid-liquid distribution systems with non-redundant selectivity, and evaluation of different approaches using liquids and solids for the isolation of target compounds from different matrices.

The influence of descriptor database selection on the solvation parameter model for separation processes

The distribution of neutral compounds in biphasic separation systems can be described by the solvation parameter model using six solute properties, or descriptors. These descriptors characterize the size (McGowan's characteristic volume), V, excess molar refraction, E, dipolarity/polarizability, S, hydrogen-bond acidity and basicity, A and B, and the gas-liquid partition constant on n-hexadecane at 298.15 K, L. McGowan's characteristic volume and the excess molar refraction for liquids are available by calculation (E requires and experimental refractive index). The other descriptors and excess molar refraction for solids are experimental quantities and subject to greater variation or are estimated using computational or empirical models. Solute descriptors for several thousand compounds are available in the Abraham descriptor database and for several hundred compounds in the WSU descriptor database. These publicly accessible databases were developed independently using different approaches and for many compounds provide different descriptor values. In this report we evaluate the effect of mixing descriptors from the two databases on modeling chromatographic retention factors and liquid-liquid partition constants. It is shown that the two descriptor databases are not interchangeable. The WSU descriptor database consistently demonstrates improved model quality as determined by statistical parameters. Model system constants exhibit a general dependence on database selection with an approximately linear trend as a function of the fraction of compounds assigned descriptors from either database. There is no general model performance advantage to using mixed descriptor datasets and no real cause for concern for relatively large datasets containing < 15 % of compounds with descriptors assigned from the other database. For small datasets, descriptor quality is an important variable for adequate model performance.

Poly-(MMA-IL) filter paper: A new class of paper-based analytical device for thin-film microextraction of multi-class antibiotics in environmental water samples using LC-MS/MS analysis

A paper-based polymeric ionic liquid (p-Poly-(MMA-IL)) was successfully developed by grafting the polymeric ionic liquid on the surface of commercial filter paper (FP) by using the dipping method, presenting a new cost-effective film. The newly developed p-Poly-(MMA-IL) FP was then applied as a paper-based thin-film microextraction (p-TFME) analytical device to extract 14 compounds as representative of five groups of antibiotic drugs, which were sulfonamides, tetracyclines, fluoroquinolones, penicillin and macrolides in environmental water samples. Besides, p-Poly-(MMA-IL) FP, p-Poly-(MMA) FP, and unmodified filter paper were successfully characterised by FTIR, NMR, FESEM, TGA, and XRD techniques. They underwent significant parameters optimisation, which affected the extraction efficiency. Under optimal conditions, the proposed (p-Poly-(MMA-IL) FP-TFME) device method was evaluated and applied to analyse multi-class antibiotic drugs in environmental water samples by using a liquid chromatography-mass spectrometry (LC-MS). The validation method showed that a good linearity (0.1 μg L^-1 - 500 μg L^-1) was noted (R² > 0.993, n = 3). Detection and quantification limits were within 0.05 μg L^-1 - 4.52 μg L^-1 and 0.15 μg L^-1 - 13.6 μg L^-1, respectively. The relative standard deviation (RSD) values ranged at 1.4%-12.2% (intra-day, n = 15) and 4.4%-11.0% (inter-day, n = 10). The extraction recoveries of environmental water samples ranged from 79.1% to 126.8%, with an RSD of less than 15.4% (n = 3). The newly developed paper-based polymeric ionic liquid (p-Poly-(MMA-IL) FP) for analysis of multi-class antibiotic drugs under the p-TFME analytical device procedure was successfully achieved with limited sample volume and organic solvent, fast extraction, and feasible in daily analysis. The detection concentration and relative RSD of multi-class antibiotics determined in various environmental water samples by the proposed method (n = 5) were within 0.44 μg L^-1 - 54.41 μg L^-1 and 0.69%-15.56%, respectively. These results signified the potential of the p-Poly-(MMA-IL) FP-TFME device as an efficient, sensitive and environmentally friendly approach for analysing antibiotics.

Recent advances for estimating environmental properties for small molecules from chromatographic measurements and the solvation parameter model

The transfer of neutral compounds between immiscible phases in chromatographic or environmental systems can be described by six solute properties (solute descriptors) using the solvation parameter model. The solute descriptors are size (McGowan's characteristic volume), V, excess molar refraction, E, dipolarity/polarizability, S, hydrogen-bond acidity and basicity, A and B, and the gas-liquid partition constant on n-hexadecane at 298.15 K, L. V and E for liquids are accessible by calculation but the other descriptors and E for solids are determined experimentally by chromatographic, liquid-liquid partition, and solubility measurements. These solute descriptors are available for several thousand compounds in the Abraham solute descriptor databases and for several hundred compounds in the WSU experimental solute descriptor database. In the first part of this review, we highlight features important in defining each descriptor, their experimental determination, compare descriptor quality for the two organized descriptor databases, and methods for estimating Abraham solute descriptors. In the second part we focus on recent applications of the solvation parameter model to characterize environmental systems and its use for the identification of surrogate chromatographic models for estimating environmental properties.

The Isolation of Specialty Compounds from Amphidinium carterae Biomass by Two-Step Solid-Phase and Liquid-Liquid Extraction

The two main methods for partitioning crude methanolic extract from Amphidinium carterae biomass were compared. The objective was to obtain three enriched fractions containing amphidinols (APDs), carotenoids, and fatty acids. Since the most valuable bioproducts are APDs, their recovery was the principal goal. The first method consisted of a solid-phase extraction (SPE) in reverse phase that, for the first time, was optimized to fractionate organic methanolic extracts from Amphidinium carterae biomass using reverse-phase C18 as the adsorbent. The second method consisted of a two-step liquid-liquid extraction coupled with SPE and, alternatively, with solvent partitioning. The SPE method allowed the recovery of the biologically-active fraction (containing the APDs) by eluting with methanol (MeOH): water (H₂O) (80:20 v/v). Alternatively, an APD purification strategy using solvent partitioning proved to be a better approach for providing APDs in a clear-cut way. When using n-butanol, APDs were obtained at a 70% concentration (w/w), whereas for the SPE method, the most concentrated fraction was only 18% (w/w). For the other fractions (carotenoids and fatty acids), a two-step liquid-liquid extraction (LLE) method coupled with the solvent partitioning method presented the best results.

Advances in the analytical methods for the determination of fluorinated aromatic carboxylic acids in aqueous matrices: A review

Fluorobenzoic acids are critically important chemical tracers in hydrothermal, geothermal, leaching, and oilfield applications. Particularly in oilfield applications, these tracers are used to investigate fluid flow paths between injector wells and producer wells, providing valuable information about the enhanced oil recovery process of the oil reservoirs. The detection limit of tracers is a vital subject in field reservoir work because the amount of chemical tracer that must be injected into the injector well is directly related to the amount detected at the producer well after migration and diffusion. The popularity of fluorinated benzoic acids as the tracers is due to their non-toxicity over radioactive tracers and low detection limit, which is determined using analytical techniques. This review focuses on the improvements/developments in extraction techniques such as solid-phase extraction and determination techniques such as gas chromatography coupled with mass spectrometry, liquid chromatography with mass spectrometry, isotope dilution gas chromatography-mass spectrometry, high-performance liquid chromatography, ion chromatography coupled with electrospray mass spectrometry, and so on for the analysis of fluorinated benzoic acids to achieve the lowest possible limit of concentration.

Effect of operating variables on the separation of radiostrontium from aqueous matrices with ion-selective solid-phase extraction systems

Radiostrontium (r-Sr: ⁹⁰Sr) is one of the primary fission products in nuclear power plants and generates liquid radioactive waste when intermixed to the aqueous matrix. Therefore, separation or preconcentration of r-Sr from the aqueous matrices is necessary for environmental monitoring or nuclear forensics. The solid-phase extraction (SPE) approach is prevalently used for r-Sr isolation and to design matrix-specific methods, while generalized SPE-assisted operating protocols are not proposed by far. In the current work, four different SPEs, namely AnaLig Sr-01, Eichrom Sr, Triskem TK100, and Eichrom DGA, were evaluated for selective separation of Sr from aqueous matrices. Operating variables, e.g., solution acidity, washing solvent, eluent-type or volume, loading or elution flow-rate, were varied to optimize the SPEs performance. The objective was to ascertain the operating variables for maximum Sr-separation yield from aqueous environmental samples with the SPEs mentioned above. In addition, the Sr-separation efficiency of SPEs was evaluated by calculating the separation factor (SF_Sr/M) between Sr and interfering elements to r-Sr (M = Ca, Mg, Ba, or Y), and the Sr-retention capacity of the SPEs was determined. Finally, the optimized operating variables for the evaluated SPEs were used to construct protocols for r-Sr separation from aqueous matrices. Real ⁹⁰Sr contaminated aqueous samples from the Chernobyl nuclear power plant cooling pond were treated by those protocols, and the results are validated comparing with the IAEA-recommended classical protocol. All the SPEs were able to isolate Sr at varying extents from matrices at the optimum conditions, even at much higher contents of interfering elements. Eichrom Sr or AnaLig Sr-01 showed better Sr-retention capability among the SPEs, while Triskem TK100 showed superiority over other SPEs regarding Sr-selectivity.

Selective Separation of Radiocesium from Complex Aqueous Matrices Using Dual Solid-Phase Extraction Systems

The release of radiocesium (r-Cs) into natural aqueous systems is of concern because of its extended solubility as an alkaline metal ion and its facile incorporation into living beings. A technique for the selective separation of Cs from an aqueous matrix using dual solid-phase extraction (SPE) systems in a series is proposed in this paper. The SPEs equipped with chelates (Nobias Chelate-PA1 and Nobias Chelate-PB1), an ion-exchange resin (Nobias Ion SC-1), or macrocycles (MetaSEP AnaLig Cs-01 and MetaSEP AnaLig Cs-02) were evaluated in terms of selectivity and retention/recovery behavior toward Cs and other potentially competing ions (Li, Na, K, Rb, Ba, Ca, Mg, and Sr). The simulated solution of ¹³³Cs, a chemical analog of r-Cs, was used to optimize the separation process. Operating parameters such as pH (3-13), flow rate (0.2-5.0 mL min^-1), and elution behavior (HCl, 0.1-5.0 mol L^-1) were optimized to ensure maximum removal of Cs from the aqueous matrices. The dual SPE system comprised Nobias Chelate-PB1 that minimized the competing impact of ions, while selective Cs retention was attained with MetaSEP AnaLig Cs-02. The proposed process was verified using real r-Cs-contaminated water from Fukushima, Japan, to observe the quantitative separation and preconcentration of r-Cs from the complex matrices.

Application of the poly (POSS-octavinyl-co-N-methylacetamide-co-divinylbenzene) solid extraction column in analyzing preservatives

In this study, a special poly solid-phase extraction (in-tube SPE) column consisting of poly (POSS-octavinyl-co-N-methylacetamide-co-divinylbenzene) [poly (POSS-OS-co-DVB-co-NMA)] was prepared based on the chemical structure of the preservatives, and was used as medium for extraction analysis in combination with UPLC. The composition of polymer SPE was optimized and characterized; good scanning electron microscopy (SEM) properties and satisfactory porosity were obtained with 30% monomer (POSS-OS:DVB:NMA = 2 wt%:13 wt%:15 wt%) and 70 wt% porogenic solvent (PEG20000:DMSO:ACN = 10 wt%:50 wt%:10 wt%). The experimental parameters of the in-tube SPE-UPLC analysis were optimized systematically. Then, the in-tube SPE-UPLC method was applied for analyzing the beverage sample, and correlation coefficients (R²) > 0.99 were obtained for the linear relationship within limits of 0.1~5.0 μg mL^-1. Excellent extraction efficiency, good precision, and satisfactory limit of detection sensitivity between 0.03 and 0.10 μg mL^-1 were obtained. The recovery ranged from 71.5 to 88.0%, with RSD ≤ 6.1%. Furthermore, the proposed method has the features of simple sample pretreatment, high throughput, rapid analysis, cost-effectiveness, and satisfactory sensitivity. Hence, the developed in-tube SPE-UPLC method based on the poly (POSS-OS-co-DVB-co-NMA) SPE column can be potentially used for simple and sensitive detection of preservatives.

Optimization of a saccharin molecularly imprinted solid-phase extraction procedure and evaluation by MIR hyperspectral imaging for analysis of diet tea by HPLC

Saccharin was determined based on a new molecularly imprinted solid-phase extraction (MISPE) procedure. The polymer was synthesized with a hybrid monomer of metacrylic acid and 3-amino propril tetraethoxysilane and saccharin as template. After the synthesis, the saccharin removal from the MIP was verified by the UV analysis of the solutions used in the template removal procedure, as well as by the direct MIP analysis using FTIR hyperspectral image and chemometrics. The residual saccharin concentrations observed in the image analysis revealed a narrow concentration distribution consistent with a homogenous material. The MISPE was performed with homemade cartridges containing 200 mg of the MIP. The results obtained with standards and diet tea samples confirmed high affinity, adsorption capacity and selectivity of the MIP. The MISPE cartridge exhibited recoveries of 100 ± 3% in six extraction cycles. The diet tea analysis showed a significant reduction of the interferences, which can considerable simplifies the HPLC-UV analysis.

A new method for the preconcentrations of U(VI) and Th(IV) by magnetized thermophilic bacteria as a novel biosorbent

This paper proposes the use of Anoxybacillus flavithermus SO-15 immobilized on iron oxide nanoparticles (NPs) as a novel magnetized biosorbent for the preconcentrations of uranium (U) and thorium (Th). The SPE procedure was based on biosorption of U(VI) and Th(IV) on a column of iron oxide NPs loaded with dead and dried thermophilic bacterial biomass prior to U(VI) and Th(IV) measurements by ICP-OES. The biosorbent characteristicswere explored using FT-IR, SEM, and EDX. Significant operational factors such as solution pH, volume and flow rate of the sample solution, amounts of dead bacteria and iron oxide nanoparticles, matrix interference effect, eluent type, and repeating use of the biosorbent on process yield were studied. The biosorption capacities were found as 62.7 and 56.4 mg g^-1 for U(VI) and Th(IV), respectively. The novel extraction process has been successfullyapplied to the tap, river, and lake water samples for preconcentrations of U(VI) and Th(IV).

Systematic Evaluation of Different Coating Chemistries Used in Thin-Film Microextraction

A systematic evaluation of eight different coatings made of solid phase extraction (SPE) and carbon-based sorbents immobilized with polyacrylonitrile in the thin-film microextraction (TFME) format using LC-MS/MS was described. The investigated coatings included graphene, graphene oxide, multi-walled carbon nanotubes (MWCNTs), carboxylated MWCNTs, as carbon-based coatings, and polystyrene-divinylbenzene (PS-DVB), octadecyl-silica particles (C18), hydrophilic-hydrophobic balance particles (HLB) and phenyl-boronic acid modified particles (PBA), as SPE-based coatings. A total of 24 compounds of diverse moieties and of a wide range of polarities (log P from -2.99 to 6.98) were selected as probes. The investigated coatings were characterized based on their extraction performance toward the selected probes at different pH values and at optimized desorption conditions. In the case of SPE-based coatings, PS-DVB and HLB exhibited a balanced extraction for compounds within a wide range of polarities, and C18 showed superior extraction recoveries for non-polar analytes. Carbon-based coatings showed high affinity for non-polar compounds given that their main driving force for extraction is hydrophobic interactions. Interestingly, among the studied carbon-based coatings, graphene oxide showed the best extraction capabilities toward polar compounds owing to its oxygen-containing groups. Overall, this work provided important insights about the extraction mechanisms and properties of the investigated coatings, facilitating the coating selection when developing new TFME applications.

Preconcentrations of Ni(II) and Pb(II) from water and food samples by solid-phase extraction using Pleurotus ostreatus immobilized iron oxide nanoparticles

The present study explores the biosorption potential of Pleurotus ostreatus immobilized magnetic iron oxide nanoparticles for solid-phase extractions of Ni(II) and Pb(II) ions from the water and food samples. It was characterized using FTIR, FE-SEM/EDX before and after analyte ions biosorption. Important operational parameters including the effect of initial pH, the flow rate of the sample solution and volume, amount of biomass and support material, interfering ions, best eluent, column reusability were studied. The biosorption capacities of fungus immobilized iron oxide nanoparticles were found as 28.6 and 32.1 mg g^-1 for Ni(II) and Pb(II), respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were achieved as 0.019 and 0.062 ng mL^-1 for Ni(II), 0.041 and 0.14 ng mL^-1 for Pb(II), respectively. The proposed method was validated by applying to certified reference materials and successfully applied for the preconcentrations of Ni(II) and Pb(II) ions from water and food samples by ICP-OES.

Development of a new strategy for studying the aroma potential of winemaking grapes through the accelerated hydrolysis of phenolic and aromatic fractions (PAFs)

Current methods for assessing grape aroma potential are based on the fast hydrolysis of precursor fractions but provide hydrolyzates of poor aromatic quality. A new strategy based on the accelerated hydrolysis of reconstituted phenolic and aromatic fractions (PAFs) extracted from grapes is herein developed. PAFs are obtained by solid phase extraction on 10 g-C18 sorbents of partially dealcoholized "mistelle", obtained from grapes treated with ethanol. Under optimal conditions, PAFs contain all aroma precursors but the most polar ones, such as those of DMS, more than 85% of the total phenolics and just traces of metal cations and of amino acids. PAFs reconstituted in model wine, aged in strict anoxia 7 weeks at 45 °C or 24 h at 75 °C, develop strong aromas. At least 30 different odorants including lipid derivatives, volatile phenols, vanillins, norisoprenoids, terpenes, bencenoids and 3-mercaptohexanol were identified by GC-Olfactometry and GC-MS. Methodological aspects of the extraction, hydrolysis and analysis are optimized and discussed.

Synthetic Peptide Purification via Solid-Phase Extraction with Gradient Elution: A Simple, Economical, Fast, and Efficient Methodology

A methodology was implemented for purifying peptides in one chromatographic run via solid-phase extraction (SPE), reverse phase mode (RP), and gradient elution, obtaining high-purity products with good yields. Crude peptides were analyzed by reverse phase high performance liquid chromatography and a new mathematical model based on its retention time was developed in order to predict the percentage of organic modifier in which the peptide will elute in RP-SPE. This information was used for designing the elution program of each molecule. It was possible to purify peptides with different physicochemical properties, showing that this method is versatile and requires low solvent consumption, making it the least polluting one. Reverse phase-SPE can easily be routinely implemented. It is an alternative to enrich and purified synthetic or natural molecules.

High throughput screening of complex biological samples with mass spectrometry – from bulk measurements to single cell analysis

We review the state of the art in HTS using mass spectrometry with minimal sample preparation from complex biological matrices. We focus on industrial and biotechnological applications.

Extraction for analytical scale sample preparation (IUPAC Technical Report)

Approaches for sample preparation are developing rapidly as new strategies are implemented to improve sample throughput and to minimize material and solvent use in laboratory methods and to develop on-site capabilities. In majority of cases the key step in sample preparation is extraction, typically used to separate and enrich compounds of interests from the matrix in the extraction phase. In this contribution, the topic of analytical scale extraction is put in perspective emphasising the fundamental aspects of the underlying processes discussing the similarities and differences between different approaches. Classification of extraction techniques according to the mass transfer principles is provided.

Glossary of terms used in extraction (IUPAC Recommendations 2016)

Approaches for analytical-scale extraction are developing rapidly as new strategies are implemented to improve sample throughput, to minimize material use in laboratory methods, and to develop on-site capabilities. In this contribution, definitions and recommendations for symbols for the terms used in analytical extraction are presented. Exhaustive, microextraction, elevated temperature, microwave- and ultrasound-assisted, parallel batch, flow through systems, and membrane extraction approaches are discussed. An associated tutorial titled “Extraction” provides a detailed introduction to the topic.

Capillary-channeled polymer (C-CP) fibers for the rapid extraction of proteins from urine matrices prior to detection with MALDI-MS

PURPOSE

While MS is a powerful tool for biomarker determinations, the high salt content and the small molecules present in urine poses incredible challenges. Separation/extraction methods must be employed for the isolation of target species at relevant concentrations. Micropipette tips packed with capillary-channeled polymer (C-CP) fibers are employed for the SPE of proteins from a synthetic and a certified urine matrix.

EXPERIMENTAL DESIGN

Extractions are performed utilizing a very simple centrifugation method to spin-down species through the C-CP fiber tips. Proteins adsorb to the hydrophobic polypropylene fibers and are eluted in a solvent suitable for MALDI-MS analysis. Figures of merit are determined for representative compounds β2-microglobulin, retinol binding protein, and transferrin.

RESULTS

The optimum protein processing included a 100 μL aqueous rinse and an elution solvent composition was 10 μL of 55:45 ACN:water (with triflouroacetic acid). MALDI-MS responses for the target proteins are improved from nondetectable levels to eventually yield LOD ranging from 5 to 180 nM in 1 μL aliquots.

CONCLUSION AND CLINICAL RELEVANCE

C-CP fiber tips offer a plethora of advantages including low materials costs, high throughput, microvolume processing, and the determination of sub-nanogram quantities of analyte; allowing determination of biomarkers that are otherwise undetectable in urine matrices.