Enhancing the Concentration Capability of Nonsupported Electrically Driven Liquid-Phase Microextraction through Programmable Flow Using an All-In-One 3D-Printed Optosensor: A Proof of Concept.

A versatile millifluidic 3D-printed inverted Y-shaped unit (3D-YSU) was prototyped to ameliorate the concentration capability of nonsupported microelectromembrane extraction (µ-EME), exploiting optosensing detection for real-time monitoring of the enriched acceptor phase (AP). Continuous forward-flow and stop-and-go flow modes of the donor phase (DP) were implemented via an automatic programmable-flow system to disrupt the electrical double layer generated at the DP/organic phase (OP) interface while replenishing the potentially depleted layers of analyte in DP. To further improve the enrichment factor (EF), the organic holding section of the OP/AP channel was bifurcated to increase the interfacial contact area between the DP and the OP. Exploiting the synergistic assets of (i) the continuous forward-flow of DP (1050 µL), (ii) the unique 3D-printed cone-shaped pentagon cross-sectional geometry of the OP/AP channel, (iii) the bifurcation of the OP that creates an inverted Y-shape configuration, and (iv) the in situ optosensing of the AP, a ca. 24 EF was obtained for a 20 min extraction using methylene blue (MB) as a model analyte. The 3D-YSU was leveraged for the unsupervised µ-EME and the determination of MB in textile dye and urban wastewater samples, with relative recoveries ≥88%. This is the first work toward analyte preconcentration in µ-EME with in situ optosensing of the resulting extracts using 3D-printed millifluidic platforms.

Modulable 3D-printed plantibody-laden platform enabling microscale affinity extraction and ratiometric front-face fluorescence detection of microcystin-LR in marine waters.

A 3D-printed stereolithographic platform for selective biorecognition is designed to enable convective microscale affinity extraction of microcystin-LR (MC-LR) followed by direct solid-phase optosensing exploiting ratiometric front-face fluorescence spectroscopy. For this purpose, a recombinant monoclonal plantibody (recAb) is covalently attached to a 3D-printed structure for sorptive immunoextraction, whereupon the free and unbound primary amino moieties of the recAb are derivatized with a fluorescent probe. The fluorophore-recAb-MC-LR laden device is then accommodated in the cuvette holder of a conventional fluorometer without any instrumental modification for the recording of the solid-phase fluorescence emission. Using Rodbard's four-parameter sigmoidal function, the 3D-printed bioselective platform features a limit of detection (LOD) of 28 ng L-1 using a sample volume of 500 mL, device-to-device reproducibility down to 12%, and relative recoveries ranging from 91 to 100% in marine waters. Printed prototypes are affordable, just 0.4 € per print and ≤ 10 € per device containing recAb. One of the main assets of the miniaturized immunoextraction device is that it performs comparably well in terms of analytical figures of merit with costly mass spectrometric-based analytical methodologies, such as HPLC-MS/MS. The device is readily applicable to high-matrix samples, such as seawater, as opposed to previous biosensing platforms, just applied to freshwater systems.

Biomimetic Dispersive Solid-Phase Microextraction: A Novel Concept for High-Throughput Estimation of Human Oral Absorption of Organic Compounds.

There is a quest for a novel in vitro analytical methodology that is properly validated for the prediction of human oral absorption and bioaccumulation of organic compounds with no need of animal models. The traditional log P parameter might not serve to predict bioparameters accurately inasmuch as it merely accounts for the hydrophobicity of the compound, but the actual interaction with the components of eukaryotic cells is neglected. This contribution proposes for the first time a novel biomimetic microextraction approach capitalized on immobilized phosphatidylcholine as a plasma membrane surrogate onto organic polymeric sorptive phases for the estimation of human intestinal effective permeability of a number of pharmaceuticals that are also deemed contaminants of emerging concern in environmental settings. A comprehensive exploration of the conformation of the lipid structure onto the surfaces is undertaken so as to discriminate the generation of either lipid monolayers or bilayers or the attachment of lipid nanovesicles. The experimentally obtained biomimetic extraction data is proven to be a superb parameter against other molecular descriptors for the development of reliable prediction models of human jejunum permeability with R2 = 0.76, but the incorporation of log D and the number of aromatic rings in multiple linear regression equations enabled improved correlations up to R2 = 0.88. This work is expected to open new avenues for expeditious in vitro screening methods for oral absorption of organic contaminants of emerging concern in human exposomics.

Automated Sequential Injection-Capillary Electrophoresis for Dried Blood Spot Analysis: A Proof-of-Concept Study.

A hyphenated analytical platform that enables fully automated analyses of dried blood spots (DBSs) is proposed by the at-line coupling of sequential injection (SI) to capillary electrophoresis (CE). The SI system, exploited herein for the first time for unattended DBS handling, serves as the "front end" mesofluidic platform for facilitating exhaustive elution of the entire DBS by flow programming. The DBS eluates are thus free from hematocrit and nonhomogeneity biases. The SI pump transfers the resulting DBS eluates into CE sample vials through an internal port of the CE instrument and homogenizes the eluates, whereupon the eluted blood compounds are automatically injected, separated, and quantified by the CE instrument. The SI and CE are commercially available off-the-shelf instruments and are interconnected through standard nuts, ferrules, and tubing without additional instrumental adjustments. They are controlled by dedicated software and are synchronized for a fully autonomous operation. The direct determination of endogenous (potassium and sodium) and exogenous (lithium as a model drug) inorganic cations in DBS samples has been used for the proof-of-concept demonstration. The hyphenated SI-CE platform provides excellent precision of the analytical method with relative standard deviation (RSD) values of peak areas below 1.5 and 3.5% for intraday and interday analyses, respectively, of the endogenous concentrations of the two inorganic cations. For the determination of lithium, calibration is linear in a typical clinical range of the drug (R2 better than 0.9993 for 2-20 mg/L), RSD values of peak areas are below 4.5% (in the entire calibration range), the limit of detection (0.4 mg/L) and the limit of quantification (1.3 mg/L) are well below the drug's minimum therapeutic concentration (4 mg/L), and total analysis time is shorter than 5 min. The SI-CE platform reflects the actual trends in the automation of analytical methods, offers rapid and highly flexible DBS elution/analysis processes, and might thus provide a general solution to modern clinical analysis as it can be applied to a broad range of analytes and dried biological materials.

Automatic and renewable micro-solid-phase extraction based on bead injection lab-on-valve system for determination of tranexamic acid in urine by UHPLC coupled with tandem mass spectrometry.

An automatic micro-solid-phase extraction (µSPE) method using on-line renewable sorbent beads followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of tranexamic acid (TXA) in urine. The µSPE method was based on the bead injection (BI) concept combined with the mesofluidic lab-on-valve (LOV) platform. All steps of the µSPE-BI-LOV were implemented by computer programming, rendering enhanced precision on time and flow events. Several parameters, including the type of sorbent, volume and composition of the conditioning solution, washing solution, and eluent composition, were evaluated to improve the extraction efficiency. The best results were obtained with a hydrophilic-lipophilic balanced mixed-mode sorbent, decorated with sulfonic acid groups (Oasis MCX), and 99% acetonitrile-water (50:50, v/v)-1% ammonium hydroxide as eluent. Chromatographic separation was performed using a BEH amide column coupled to MS/MS detection in positive ionization mode. Good linearity was achieved (R2 > 0.998) for TXA concentrations in urine ranging from 300 to 3000 ng mL-1, with LOD and LOQ of 30 and 65 ng mL-1, respectively. Dilution integrity was observed for dilution factors up to 20,000 times, providing the extension of the upper limit of quantification to 12 mg mL-1. The method was validated according to international guidelines and successfully applied to urine samples collected during scoliosis surgery of pediatric patients treated with TXA.

3D printed spinning cup-shaped device for immunoaffinity solid-phase extraction of diclofenac in wastewaters.

This article reports current research efforts towards designing bespoke microscale extraction approaches exploiting the versatility of 3D printing for fast prototyping of novel geometries of sorptive devices. This is demonstrated via the so-called 3D printed spinning cup-based platform for immunoextraction of emerging contaminants using diclofenac as a model analyte. A new format of rotating cylindrical scaffold (containing a semispherical upper cavity) with enhanced coverage of biorecognition elements, and providing elevated enhancement factors with no need of eluate processing as compared with other microextraction stirring units is proposed. Two distinct synthetic routes capitalized upon modification of the acrylate surface of stereolithographic 3D printed parts with hexamethylenediamine or branched polyethyleneimine chemistries were assayed for covalent binding of monoclonal diclofenac antibody.Under the optimized experimental conditions, a LOD of 108 ng L-1 diclofenac, dynamic linear range of 0.4-1,500 µg L-1, and enrichment factors > 83 (for near-exhaustive extraction) were obtained using liquid chromatography coupled with UV-Vis detection. The feasibility of the antibody-laden device for handling of complex samples was demonstrated with the analysis of raw influent wastewaters with relative recoveries ranging from 102 to 109%. By exploiting stereolithographic 3D printing, up to 36 midget devices were fabricated in a single run with an estimated cost of mere 0.68 euros per 3D print and up to 16 €/device after the incorporation of the monoclonal antibody.

An automatic flow-through system for exploration of the human bioaccessibility of endocrine disrupting compounds from microplastics.

This article reports on the first attempt towards investigating the leaching rates in the human gastrointestinal (GI) tract of plastic-borne contaminants that can be ingested accidentally using physiologically relevant body fluids. Oral bioaccessibility under fasted and fed states was determined in dynamic mode exploiting an automatic flow setup. The flow system is able to mimic the fast uptake of the released species from the polymeric matrix by absorption in the human digestive system by the in-line removal of the leached species. Complex GI extractants based on the Unified Bioaccessibility Method (UBM, fasted state) and Versantvoort test (fed-state) were brought through a microplastic-loaded metal microcolumn for semi-continuous leaching of plasticizers (phthalic acid ester congeners) and monomer/antioxidant species (bisphenol A, BPA) followed by in-line solid-phase extraction and clean-up of GI extracts prior to liquid chromatography analysis. The temporal extraction profiles were fitted to a first-order kinetic model for the estimation of maximum bioaccessibility pools and apparent leaching rates. Among all studied contaminants, only BPA, dimethylphthalate and diethylphthalate were appreciably released under dynamic GI conditions from high-density polyethylene pellets (average size of 110 µm), with average bioaccessibility values spanning from 51 to 84% and 48 to 87% for UBM and Versantvoort methods, respectively. No statistically significant differences in oral bioaccessibility pools were found under fed- and fasted-state dynamic extractions. The apparent kinetic constants under the fed state were greater by ≥30% as a consequence of the effect of the larger amounts of bile salts and digestive enzymes in the Versantvoort test on the leaching rates. The estimated average daily intake, in which bioaccessibility data are contemplated, indicated that plastic materials exceeding 0.3% (w/w) BPA might pose real risks to human health.

High-throughput microscale extraction using ionic liquids and derivatives: A review.

Ionic liquids and derivatives-mainly polymeric ionic liquids and magnetic ionic liquids-have been extensively used in microscale extraction over the past few years. Current trends in analytical sample preparation gear toward linking microextraction approaches with high-throughput sample processing to comply with green analytical chemistry requirements. A variety of high sample throughput strategies that are coupled to both ionic-liquid-based solid-phase microextraction and ionic liquid-based liquid-phase microextraction are herein reported. The review is focused on microscale extraction methods that use (i) custom-made and dedicated extraction devices, (ii) parallel extraction, (iii) magnetic-based separation, and (iv) miniaturized systems employing semi-automatic or fully automatic flow injection methods, related micro/millifluidic devices, and robotic equipment.

Automatic Mesofluidic System Combining Dynamic Gastrointestinal Bioaccessibility with Lab-on-Valve-Based Sorptive Microextraction for Risk Exposure of Organic Emerging Contaminants in Filter-Feeding Organisms.

An automatic mesofluidic system combining dynamic oral bioaccessibility with lab-on-valve (LOV)-based sorptive microextraction is herein proposed for the first time for exploring the kinetics of leaching of incurred rather than spiked organic emerging contaminants (viz., methyl paraben, butyl paraben, diclofenac, and triclosan) from exposed mussels on the basis of the Versantvoort's fed-state physiological extraction test. Our method capitalizes on programmable flow analysis, in which gastrointestinal extracts are obtained online by pumping a simulated biorelevant gastrointestinal fluid across a large-bore column (maintained at 37.0 ± 2.0 °C) loaded with 250 mg of freeze-dried and powdered mussel onto a polyvinyldiene difluoride filter membrane. The physiologically relevant extracts are then cleaned up, and the analytes are preconcentrated onto a dedicated reversed-phase solid-phase extraction (Oasis PRIME-HLB) microcolumn that is captured into the channels of an LOV mesofluidic platform. The aim behind this is to obtain analyte-laden eluates with ACN/MeOH (90:10, v/v) in unsupervised mode for direct injection into LC-MS. The LOV minicolumn (≤25 mg) is automatically disposed of and renewed for every individual fraction on account of the strong retention of (phospho)lipids by the copolymeric sorbent. The proposed dynamic bioaccessibility test features a significant shortening of the extraction time against the batch method (28 vs 240 min) while avoiding overestimation of potentially bioavailable fractions. The trueness of the online gastrointestinal extraction method was confirmed using mass-balance validation following ultrasonic-assisted solid-liquid extraction of the original mussel sample and the residual (nonbioaccessible) fraction of emerging contaminants.

3D Printing: The Second Dawn of Lab-On-Valve Fluidic Platforms for Automatic (Bio)Chemical Assays.

In this work, inexpensive manufacturing of unibody transparent mesofluidic platforms for pressure-driven Lab-On-a-Valve (LOV) methodologies is accomplished via rapid one-step 3D prototyping from digital models by user-friendly freeware. Multichannel architecture having 800-1800 µm cross-sectional features with unconventional 3D conduit structures and integrating optical and electrochemical detection facilities is for the first time reported. User-defined flow-programming capitalizing upon software control for automatic liquid handling is synergistically combined with additive manufacturing based on stereolithographic 3D printing so as to launch the so-called fourth generation of microflow analysis (3D-µFIA). Using an affordable consumer-grade 3D printer dedicated LOV platforms are 3D printed at will and prints are characterized in terms of solvent compatibility, optical and mechanical properties, and sorption of inorganic and organic species to prospect potentialities for the unfettered choice of chemistries. The unique versatility of the 3D-printed LOV device that is attached to a multiposition rotary valve as a central design unit is demonstrated by (i) online handling of biological materials followed by on-chip photometric detection, (ii) flow-through bioaccessibility tests in exposome studies of contaminated soils with miniaturized voltammetric detection, (iii) online phospholipid removal by TiO2-incorporated microextraction approaches using on-chip disposable sorbents, and (iv) automatic dynamic permeation tests mimicking transdermal measurements in Franz-cell configurations. A multipurpose LOV fluidic platform can be fabricated for less than 11 Euros.

Fully Automated Electric-Field-Driven Liquid Phase Microextraction System with Renewable Organic Membrane As a Front End to High Performance Liquid Chromatography.

This article reports for the first time a programmable-flow-based mesofluidic platform that accommodates electric-field-driven liquid phase microextraction (µ-EME) in a fully automated mode. The miniaturized system is composed of a computer-controlled microsyringe pump and a multiposition rotary valve for handling aqueous and organic solutions at a low microliter volume and acts as a front-end to online liquid chromatographic separation. The organic membrane is automatically renewed and disposed of in every analytical cycle, thus minimizing analyte carry-over effects while avoiding analyst intervention. The proof-of-concept applicability of the automated mesofluidic device is demonstrated by the liquid chromatographic determination of nonsteriodal anti-inflammatory drugs in µ-EME processed complex samples (such as urine and influent wastewater) using online heart-cut approaches. Using 5 µL of 1-octanol, 7.5 µL of untreated sample and 7.5 µL of acceptor solution (25 mM NaOH), and 250 V for only 10 min in a stopped-flow mode, the extraction recoveries for the µ-EME of ibuprofen, ketoprofen, naproxen, and diclofenac exceed 40% in real samples. The flow-through system features moderately selective extraction regardless of the sample matrix constituents with repeatability values better than 13%.

Reliable Sensing Platform for Plasmonic Enzyme-Linked Immunosorbent Assays Based on Automatic Flow-Based Methodology.

Plasmonic enzyme-linked immunosorbent assays (ELISA) using the localized surface plasmon resonance (LSPR) of metal nanoparticles has emerged as an appealing alternative to conventional ELISA counterparts for ultrasensitive naked-eye detection of biomolecules and small contaminants. However, batchwise plasmonic ELISA involving end-point detection lacks ruggedness inasmuch as the generation or etching of NP is greatly dependent on every experimental parameter of the analytical workflow. To tackle the above shortcomings, this paper reports on an automatic flow methodology as a reliable detection scheme of hydrogen peroxide related enzymatic bioassays for ultrasensitive detection of small molecules. Here, a competitive ELISA is combined with the in-line generation of plasmonic gold nanoparticles (AuNPs) followed by the real-time monitoring of the NP nucleation and growth rates and size distribution using a USB miniaturized photometer. Glucose oxidase was labeled to the secondary antibody and yielded hydrogen peroxide that acted as the measurand and the reducing agent of the Au(III)/citrate system in the flow network. High-throughput plasmonic assays were feasible by assembling a hybrid flow system composed of two microsyringe pumps, a perfluoroalkoxy alkane reaction coil, and a 26-port multiposition valve and operated under computer-controllable flow conditions. The ultratrace determination of diclofenac in high matrix samples, e.g., seawater, without any prior sample treatment was selected as a proof-of-concept application of the flow-based platform for determination of emerging contaminants via plasmonic ELISA. The detection limit (0.001 µg L-1) was 1 order of magnitude lower than that endorsed by the first EU Watch List for diclofenac as a potentially emerging contaminant in seawater and also than that of a conventional colorimetric ELISA, which in turn is inappropriate for determination of diclofenac in seawater at the levels endorsed by the EU regulation. The proposed automatic fluidic approach is characterized by the reproducible timing in AuNPs nucleation and growth along with the unsupervised LSPR absorbance detection of AuNPs with a dynamic range for diclofenac spanning from 0.01 to 10 µg L-1. Repeatability and intermediate precision (given as normalized signal readouts) in seawater were <4% and <14%, respectively, as compared to RSDs as high as 30% as obtained with the batchwise plasmonic ELISA counterpart.

Modeling Dispersal of UV Filters in Estuaries.

Lagrangian ocean analysis, where virtual parcels of water are tracked through hydrodynamic fields, provides an increasingly popular framework to predict the dispersal of water parcels carrying particles and chemicals. We conduct the first direct test of Lagrangian predictions for emerging contaminants using (1) the latitude, longitude, depth, sampling date, and concentrations of UV filters in raft cultured mussel ( Mytilus galloprovincialis) of the estuary Ria de Arousa, Spain (42.5°N, 8.9°W); (2) a hydrodynamic numerical model at 300 m spatial resolution; and (3) a Lagrangian dispersion scheme to trace polluted water parcels back to pollution sources. The expected dispersal distances (mean ± SD) are 2 ± 1 km and the expected dispersal times (mean ± SD) are 6 ± 2 h. Remarkably, the probability of dispersal of UV filters from potential sources to rafts decreases 5-fold over 5 km. In addition to predicting dispersal pathways and times, this study also provides a framework for quantitative investigations of concentrations of emerging contaminants and source apportionment using turbulent diffusion. In the coastline, the ranges of predicted concentrations of the UV-filters 4-methylbenzylidene-camphor, octocrylene, and benzophenone-4 are 3.2 × 10-4 to 0.023 ng/mL, 2.3 × 10-5 to 0.009 ng/mL, and 5.6 × 10-4 to 0.013 ng/mL, respectively. At the outfalls of urban wastewater treatment plants these respective ranges increase to 8.9 × 10-4 to 0.07 ng/mL, 6.2 × 10-5 to 0.027 ng/mL, and 1.6 × 10-3 to 0.040 ng/mL.

Lab-on-a-Valve Mesofluidic Platform for On-Chip Handling of Carbon-Coated Titanium Dioxide Nanotubes in a Disposable Microsolid Phase-Extraction Mode.

Mesofluidic lab-on-a-valve (LOV) platforms have been proven suitable to accommodate automatic micro-solid-phase extraction (µSPE) approaches with on-chip handling of micrometer-bead materials in a fully disposable mode to prevent sample cross-contamination and pressure-drop effects. The efficiency of the extraction process notably depends upon the sorptive capacity of the material because the sorbent mass is usually down to 10 mg in LOV devices. Nanomaterials, capitalizing upon their enhanced surface-to-volume ratio and diversity of potential chemical moieties, are appealing alternatives to microbead sorbents. However, the handling and confinement of nanomaterials in fluidic chip structures have been challenging to date. This is most likely a consequence of the aggregation tendency of a number of nanomaterials, including carbon-based sorbents, that leads to excessive back-pressure in flowing systems along with irreproducible bead loading. This paper addresses these challenges by ad hoc synthesis of hybrid nanomaterials, such as porous carbon-coated titanium dioxide nanotubes (TiO2-NT@pC). Tailoring of the surface polarity of the carbon coating is proven to foster the dispersion of TiO2-NT@pC in LOV settings while affording superior extraction capability of moderately nonpolar species from aqueous matrices. The determination of trace-level concentrations of butylparaben (BPB) and triclosan (TCS) in seawater samples is herein selected as a proof-of-concept of the exploitation of disposable nanomaterials in LOV. The mesofluidic platform accommodating µSPE features online hyphenation to liquid chromatography/tandem mass spectrometry (LC/MS/MS) for reliable determination of the target analytes with excellent limits of detection (0.5 and 0.6 ng/L for BPB and TCS, respectively) and intermediate precision (relative standard deviation <5.8%). For 5.0 mL of sample and 200 µL of eluent, enrichment factors of 23 and 14 with absolute extraction efficiencies of 90% ± 14% and 58 ± 8% for BPB and TCS, respectively, were obtained. The relative recovery values of 107% (BPB) and 97% (TCS) in seawater demonstrate the applicability of online LOV-LC/MS/MS using TiO2-NT@pC for handling troublesome environmental samples.

Where are modern flow techniques heading to?

This article aims to provide an overview on the transition from earlier laboratory automation using analytical flow approaches toward today's applications of flow methodologies, recent developments, and future trends. The article is directed to flow practitioners while serving as a valuable reference to newcomers in the field in providing insight into flow techniques and conceptual differences in operation across the distinct flow generations. In the focus are the recently developed and complementary techniques Lab-On-Valve and Lab-In-Syringe. In the following, a brief comparison of the different application niches and contributions of flow techniques to past and modern analytical chemistry is given, including (i) the development of sample pretreatment approaches, (ii) the potential applicability for in-situ/on-site monitoring of environmental compartments or technical processes, (iii) the ability of miniaturization of laboratory chemistry, (iv) the unique advantages for implementation of kinetic assays, and finally (v) the beneficial online coupling with scanning or separation analytical techniques. We also give a critical comparison to alternative approaches for automation based on autosamplers and robotic systems. Finally, an outlook on future applications and developments including 3D prototyping and specific needs for further improvements is given. Graphical abstract ᅟ.

3D-Printed Microflow Injection Analysis Platform for Online Magnetic Nanoparticle Sorptive Extraction of Antimicrobials in Biological Specimens as a Front End to Liquid Chromatographic Assays.

In this work, the concept of 3D-printed microflow injection (3D-µFI) embodying a dedicated multifunctional 3D-printed stator onto a rotary microvalve along with a mesofluidic sample preparation platform is proposed for the first time. A transparent 3D-printed stereolithographic mesofluidic chip device accommodating polyaniline (PANI) decorated magnetic nanoparticles (32.5 ± 3.8 mg) is harnessed to in-line sorptive microextraction as a front end to liquid chromatography with peak focusing. As a proof-of-concept application, the 3D-µFI assembly was resorted to matrix cleanup and automatic programmable-flow determination of organic emerging contaminants (4-hydroxybenzoate analogues and triclosan as antimicrobial model analytes) in human saliva and urine samples. By using a sample volume of 1.0 mL with a loading flow rate of 200 µL min-1, an eluent volume of 120 µL at 80 µL min-1, and online HPLC injection of 300 µL of the mixture of eluate and Milli-Q water (in a 1:2 ratio) to prevent band broadening effects of the most polar analytes, the limits of detection (3σ criterion) ranged from 1.1 to 4.5 ng mL-1 for methylparaben (MP), ethylparaben (EP), propylparaben (PrP), phenylparaben (PhP), butylparaben (BP), and triclosan (TCS). Enhancement factors of 16-25 were obtained for the target analytes. Spike recoveries ranged from 84 to 117% for both saliva and urine samples. The online 3D-µFI hyphenated method is synchronized with the chromatographic separation and features a chip lifetime of more than 20 injections with minimal losses of moderately nonpolar compounds on the walls of the mesofluidic device.

Fully Automatic In-Syringe Magnetic Stirring-Assisted Dispersive Liquid-Liquid Microextraction Hyphenated to High-Temperature Torch Integrated Sample Introduction System-Inductively Coupled Plasma Spectrometer with Direct Injection of the Organic Phase.

A proof of concept study involving the online coupling of automatic dispersive liquid-liquid microextraction (DLLME) to inductively coupled plasma optical emission spectrometry (ICP OES) with direct introduction and analysis of the organic extract is herein reported for the first time. The flow-based analyzer features a lab-in-syringe (LIS) setup with an integrated stirring system, a Meinhard nebulizer in combination with a heated single-pass spray chamber, and a rotary injection valve, used as an online interface between the microextraction system and the detection instrument. Air-segmented flow was used for delivery of a fraction of the nonwater miscible extraction phase, 12 µL of xylene, to the nebulizer. All sample preparative steps including magnetic stirring assisted DLLME were carried out inside the syringe void volume as a size-adaptable yet sealed mixing and extraction chamber. Determination of trace level concentrations of cadmium, copper, lead, and silver as model analytes has been demonstrated by microextraction as diethyldithiophosphate (DDTP) complexes. The automatic LIS-DLLME method features quantitative metal extraction, even in troublesome sample matrixes, such as seawater, salt, and fruit juices, with relative recoveries within the range of 94-103%, 93-100%, and 92-99%, respectively. Furthermore, no statistically significant differences at the 0.05 significance level were found between concentration values experimentally obtained and the certified values of two serum standard reference materials.

On-line dynamic extraction system hyphenated to inductively coupled plasma optical emission spectrometry for automatic determination of oral bioaccessible trace metal fractions in airborne particulate matter.

For a realistic evaluation of the potential hazard emanating from airborne particulate matter (APM), the determination of the total inhaled metal amounts associated with APM is insufficient in risk assessment. Additional information about metal fractions that can be mobilized by the human body is necessary, because only those soluble (also called bioaccessible) fractions can be absorbed by the human body, and thus potentially cause adverse health effects. In the present study, a dynamic flow-through approach as a front end to inductively coupled plasma optical emission spectrometry (ICP-OES) exploiting advanced flow analysis is employed for on-line handling of multiple APM samples and determination of bioaccessible trace metals under worst case extraction scenarios. The method is based on on-line continuous extraction of filter samples with synthetic gastric fluid followed by on-line ICP-OES measurement of the dissolved fraction of trace metals. The assembly permits an automated successive measurement of three sample replicates in less than 19 min. The on-line extraction procedure offers increased sample throughput and reduced risk of sample contamination and overcomes metal re-adsorption processes compared to the traditional batch-wise counterparts. Furthermore, it provides deeper information on the kinetics of the leaching process. The developed procedure was applied to the determination of bioaccessible metal fractions (Al, Ba, Cu, Fe and Mn as model analytes) in PM10 samples from Palma de Mallorca (Spain) and Vienna (Austria). Graphical Abstract On-line gastric bioaccessibility of elements in airborne particulate matter.

Fluorescent Lipid Nanoparticles as Biomembrane Models for Exploring Emerging Contaminant Bioavailability Supported by Density Functional Theory Calculations.

Experimental sensing schemes and thermodynamic in-silico studies are combined holistically in this manuscript so as to give new insights into the bioavailability of environmental contaminants via permeation across lipid nanoparticles (liposomes) as a mimicry of biological membranes. Using Prodan and Laurdan as fluorescent membrane probes, phosphatidylcholine-based unilamellar liposomes are harnessed to investigate membranotropic effects of alkyl esters of p-hydroxybenzoic acid and triclosan in vitro on the basis of steady-state fluorescence anisotropy, light scattering, and generalized polarization measurements. The feasibility of the analytical responses to ascertain differences in temperature-dependent contaminant bioavailability is investigated in detail. High level density functional theory (DFT) calculations (RI-BP86-D3/def2-SVP) have been resorted to investigate noncovalent 1:1 complexes of the fluorescent probes and emerging contaminants with dipalmitoylphosphatidylcholine, as a minimalist model of a lipid nanoparticle, to evaluate both the interaction energies and the geometries of the complexes. This information can be related to the degree of penetration of the guest across the lipid bilayer. Our experimental results supported by in-silico DFT calculations and ecotoxicological data let us to conclude that simple analytical measurements of liposomal changes in lipid packaging, permeability, and fluidity are appropriate to foresee the potential bioavailability and toxicity of emerging contaminants.