Headspace versus Direct Immersion Solid Phase Microextraction in Complex Matrixes: Investigation of Analyte Behavior in Multicomponent Mixtures

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.analchem.5b01850This work aims to investigate the behavior of analytes in complex mixtures and matrixes with the use of solid-phase microextraction (SPME). Various factors that influence analyte uptake such as coating chemistry, extraction mode, the physicochemical properties of analytes, and matrix complexity were considered. At first, an aqueous system containing analytes bearing different hydrophobicities, molecular weights, and chemical functionalities was investigated by using commercially available liquid and solid porous coatings. The differences in the mass transfer mechanisms resulted in a more pronounced occurrence of coating saturation in headspace mode. Contrariwise, direct immersion extraction minimizes the occurrence of artifacts related to coating saturation and provides enhanced extraction of polar compounds. In addition, matrix-compatible PDMS-modified solid coatings, characterized by a new morphology that avoids coating fouling, were compared to their nonmodified analogues. The obtained results indicate that PDMS-modified coatings reduce artifacts associated with coating saturation, even in headspace mode. This factor, coupled to their matrix compatibility, make the use of direct SPME very practical as a quantification approach and the best choice for metabolomics studies where wide coverage is intended. To further understand the influence on analyte uptake on a system where additional interactions occur due to matrix components, ex vivo and in vivo sampling conditions were simulated using a starch matrix model, with the aim of mimicking plant-derived materials. Our results corroborate the fact that matrix handling can affect analyte/matrix equilibria, with consequent release of high concentrations of previously bound hydrophobic compounds, potentially leading to coating saturation. Direct immersion SPME limited the occurrence of the artifacts, which confirms the suitability of SPME for in vivo applications. These findings shed light into the implementation of in vivo SPME strategies in quantitative metabolomics studies of complex plant-based systems.The Natural Sciences and Engineering Research Council of Canada (NSERC) Sigma-Aldrich Corporatio

Direct immersion solid-phase microextraction analysis of multi-class contaminants in edible seaweeds by gas chromatography-mass spectrometry

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.aca.2018.05.066 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The present work aimed at the development of a simple and accurate direct immersion-solidphase microextraction-gas-chromatography-mass spectrometry (DI-SPME-GC-MS) method for simultaneous determination of PAHs, PCBs, and pesticide residues in edible seaweeds. As the target contaminants possess a wide range of physical-chemical properties, multivariate experimental design was used for method optimization. In particular, two different methods were optimized and validated: one that allows for simultaneous determination of all targets, and an ad hoc method for determination of hydrophobic analytes, a class that often poses a challenge for extraction from food matrices. Optimum conditions suitable for simultaneous quantitation of all targeted compounds, namely buffer at pH = 7.0, 20% acetone (v/v), 10% NaCl (w/w), 0.02% NaN3, 60 min DI extraction at 55 °C, and 20 min desorption at 270 °C, afforded limits of quantitation (LOQs) in the range of 1–30 μg kg−1, a wide linear range of 5–2000 μg kg−1, the attainment of satisfactory determination coefficients (R2˃0.99) with no significant lack of fit (p > 0.05) at the 5% level, and satisfactory accuracy and precision values. By modifying the extraction conditions to favor extraction of the most hydrophobic analytes (e.g. higher amount of organic modifier and pH, and lower salt content) lower LOQs were obtained for these compounds ranging from 0.2 to 13.3 μg kg−1. The established methods were then used for screening of commercial, edible dry seaweeds, with PCBs (≤16.0 ng g−1) and PAHs (≤15.5 ng g−1) detected in some samples. This method overcomes most challenges commonly encountered in dry sample analysis applications, and represents the first report of a DI-SPME method employing the matrix-compatible fiber for simultaneous multiclass and multiresidue analysis of seaweeds.Natural Sciences and Engineering Research Council of CanadaChina Sponsorship Council ["201606330026"]Fundação de Amparo à Pesquisa do Estado de São Paulo ["2016/16180–6"

New Generation of Solid-Phase Microextraction Coatings for Complementary Separation Approaches: A Step toward Comprehensive Metabolomics and Multiresidue Analyses in Complex Matrices

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.analchem.6b04690In this work, a new generation of solid-phase microextraction (SPME) coatings based on polytetrafluoro-ethylene amorphous fluoroplastics (PTFE AF 2400) as a particle binder is presented. The developed coating was tested for thermal and solvent-assisted desorption, demonstrating its compatibility with both gas- and liquid-chromatographic platforms. The incorporation of hydrophilic-lipophilic balance (HLB) adsorptive particles provided optimal extraction coverage for analytes bearing a broad range of hydrophobicities and molecular weights and of varied chemical diversity. The performance of the newly developed coating was compared to already established coatings based on different polymers such as divinylb enzene/carboxen/polydimethylsiloxane (DVB/Car/ PDMS) and octadecyl/benzenesulfonic acid/polyacrylonitrile (C18/SCX/PAN) in order to assess the new prototype versus the existing technology. As this is the first documented instance of PTFE AF being used as a particle immobilizer for SPME, an assessment of the analyte uptake rate and extraction capability of the developed coating was carried out in comparison to other conventionally used polymers. Moreover, the new SPME probes were used to validate an analytical method for deteimination of banned doping substances, achieving limits of quantitation below the minimum required performance limits (MRPLs) set by the World Anti-Doping Agency (WADA) for most compounds. Considering the broad coverage of the coating in terms of analytes extracted and its suitability for both thermal- and solvent assisted desorption, these new SPME probes will properly suit various metabolomics applications that involve the use of both gas- and liquid-chromatography

A new and efficient Solid Phase Microextraction approach for analysis of high fat content food samples using a matrix-compatible coating

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.talanta.2017.01.064 © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The current work presents the optimization of a protocol enabling direct extraction of avocado samples by a new Solid Phase Microextraction matrix compatible coating. In order to further extend the coating life time, pre-desorption and post-desorption washing steps were optimized for solvent type, time, and degree of agitation employed. Using optimized conditions, lifetime profiles of the coating related to extraction of a group of analytes bearing different physical-chemical properties were obtained. Over 80 successive extractions were carried out to establish coating efficiency using PDMS/DVB 65 mu m commercial coating in comparison with the PDMS/DVB/ PDMS. The PDMS/DVB coating was more prone to irreversible matrix attachment on its surface, with consequent reduction of its extractive performance after 80 consecutive extractions. Conversely, the PDMS/DVB/PDMS coating showed enhanced inertness towards matrix fouling due to its outer smooth PDMS layer. This work represents the first step towards the development of robust SPME methods for quantification of contaminants in avocado as well as other fatty-based matrices, with minimal sample pre-treatment prior to extraction. In addition, an evaluation of matrix components attachment on the coating surface and related artifacts created by desorption of the coating at high temperatures in the GC-injector port, has been performed by GCxGC-ToF/MS.Natural Sciences and Engineering Research Council of Canada (NSERC)Sigma-Aldrich Corp

Development of Needle Trap Technology for On-Site Determinations: Active and Passive Sampling

This study presents a thorough evaluation of new prototypes of extended tip needle trap devices (NT), as well as their application to in situ sampling of biological emissions and active/passive on-site sampling of indoor air. A new NT prototype was constructed with a side hole above the sorbent and an extended tip that fits inside the restriction of the narrow neck liner to increase desorption efficiency.New prototype needles were initially packed with divinylbenzene particles at SGE Analytical Science for the purpose of studying biogenic emissions of pine trees. Prior to their final application, they were evaluated in terms of robustness after multiple use (n ˃ 10), as well as amount extracted of volatile organic compounds (VOCs). An ANOVA test for all the probes showed that at a 95 % level of confidence, there were not statistical differences observed among the 9 NTs tested. In addition, the needles were also packed in laboratory with synthesized highly cross linked PDMS as a frit to immobilize carboxen (Car) particles for spot sampling. For passive sampling, the needles were packed with Car particles embedded in PDMS in order to simplify calculations in passive mode. The use of NTs as spot samplers, as well as a passive sampler under controlled conditions in the laboratoryyielded a relative standard deviation of less than 15 %. Finally, a new, reusable and readily deployable pen-like diffusive sampler for needle traps (PDS-NT) was built and tested. Application of the PDS-NT in combination with NT-spot sampling towards the analysis of indoor air in a polymer synthesis laboratory showed good agreement between both techniques for the analyte studied, yielding averages of 0.03 ng/mL and 0.025 ng/mL of toluene, respectively.NSERC Industrial Research Chair || NSERC IRCPJ/184412-10 05016

Development and validation of a fully automated solid phase microextraction high throughput method for quantitative analysis of multiresidue veterinary drugs in chicken tissue

The final publication is available at Elsevier via https://doi.org/10.1016/j.aca.2018.12.044. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper presents the development and validation of a fully automated, high-throughput multiclass, multiresidue method for quantitative analysis of 77 veterinary drugs in chicken muscle via direct immersion solid phase microextraction (DI-SPME) and ultra-high pressure liquid chromatography-electrospray ionization - tandem mass spectrometry (UHPLC-ESI-MS/MS). The selected drugs represent more than 12 different classes of drugs characterized by varying physical and chemical properties. A Hydrophilic–lipophilic balance (HLB)/polyacrylonitrile (PAN) extraction phase, prepared using HLB particles synthesized in-house, yielded the best extraction/desorption performance among four different SPME extraction phases evaluated in the current work. The developed SPME method was optimized in terms of SPME coating and geometry, desorption solvent, extraction and rinsing conditions, and extraction and desorption times. Multivariate analysis was performed to determine the optimal desorption solvent for the proposed application. The developed method was validated according to the Food and Drug Administration (FDA) guidelines, taking into account Canadian maximum residue limits (MRLs) and US maximum tolerance levels for veterinary drugs in meat. Method accuracy ranged from 80 to 120% for at least 73 compounds, with relative standard deviation of 1–15%. Inter-day precision ranged from 4 to 15% for 70 compounds. Determination coefficients values were higher than 0.991 for all compounds under study with no significant lack of fit (p > 0.05) at the 5% level. In terms of limits of quantitation, the method was able to meet both Canadian and US regulatory levels for all compounds under study.The authors would like to acknowledge Perkin Elmer for the financial support and the staff at the University of Waterloo's Science Technical Services for their exceptional technical support and collaboration to improve the SPME brush of the high-throughput system. V.A.J.thanks FAPESP, process 2016/16180e6 for his scholarship

Coupling solid phase microextraction to complementary separation platforms for metabotyping of E. coli metabolome in response to natural antibacterial agents

The final publication is available at Springer via http://dx.doi.org/10.1007/s11306-016-1111-9Introduction Essential oils are known to possess antimicrobial activity; thus, their use has played an important role over the years in medicine and for food preservation purposes. Objective The effect of clove oil and its major constituents as bactericidal agents on the global metabolic profiling of E. coli bacteria was assessed by means of metabolic alterations, using solid phase microextraction (SPME) as a sample preparation method coupled to complementary analytical platforms. Method E. Coli cultures treated with clove oil and its major individual components were sampled by HS-SPME-GCxGC-ToF/MS and SPME-UPLC-MS. Full factorial design was applied in order to estimate the most effective antibacterial agent towards E. coli. Central composite design and factorial design were applied to investigate parameters influencing metabolite coverage and efficiency by SPME. Results The metabolic profile, including 500 metabolites identified by LC-MS and 789 components detected by GCxGC-ToF/MS, 125 of which were identified as dys-egulated metabolites, revealed changes in the metabolome provoked by the antibacterial activity of clove oil, and in particular its major constituent eugenol. Analyses of individual components selected using orthogonal projections to latent structures discriminant analysis showed a neat differentiation between control samples in comparison to treated samples in various sets of metabolic pathways. Conclusions The combination of a sample preparation method capable of providing cleaner extracts coupled to different analytical platforms was successful in uncovering changes in metabolic pathways associated with lipids biodegradation, changes in the TCA cycle, amino acids, and enzyme inhibitors in response to antibacterial treatment.Natural Sciences and Engineering Research Council (NSERC) of CanadaCNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico), Brazi

Methodical evaluation and improvement of matrix compatible PDMS-overcoated coating for direct immersion solid phase microextraction gas chromatography (DI-SPME-GC)-based applications

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.aca.2016.03.015 © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The main quest for the implementation of direct SPME to complex matrices has been the development of matrix compatible coatings that provide sufficient sensitivity towards the target analytes. In this context, we present here a thorough evaluation of PDMS-overcoated fibers suitable for simultaneous extraction of different polarities analytes, while maintaining adequate matrix compatibility. For this, eleven analytes were selected, from various application classes (pesticides, industrial chemicals and pharmaceuticals) and with a wide range of log P values (ranging from 1.43 to 6). The model matrix chosen was commercial Concord grape juice, which is rich in pigments such as anthocyanins, and contains approximately 20% of sugar (w/w). Two types of PDMS, as well as other intrinsic factors associated with the PDMS-overcoated fiber fabrication are studied. The evaluation showed that the PDMS-overcoated fibers considerably slowed down the coating fouling process during direct immersion in complex matrices of high sugar content. Longevity differences could be seen between the two types of PDMS tested, with a proprietary Sylgard (R) giving superior performance because of lesser amount of reactive groups and enhanced hydrophobicity. Conversely, the thickness of the outer layer did not seem to have a significant effect on the fiber lifetime. We also demonstrate that the uniformity of the overcoated PDMS layer is paramount to the achievement of reliable data and extended fiber lifetime. Employing the optimum overcoated fiber, limits of detection (LOD) in the range of 0.2-1.3 ng/g could be achieved. Additional improvement is attainable by introducing washing of the coatings after desorption, so that any carbon build-up (fouling) left on the coating surface after thermal desorption can be removed.Natural Sciences and Engineering Research Council of Canada (NSERC

Development and validation of eco-friendly strategies based on thin film microextraction for water analysis

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.chroma.2018.10.026 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The aim of the current study is the establishment of Green Analytical Chemistry strategies for water analysis by elimination/reduction of hazardous chemicals, energy consumption, and waste generation throughout the entire analytical workflow. The first approach introduced in this manuscript consists of addition of water to a sampling vessel that contains a thin film microextraction (TFME) device, followed by removal of the device after equilibration, and subsequent quantification of the extracted components by thermal desorption GC/MS. In this approach, namely the in-bottle TFME approach, analyte-loss associated errors that stem from analyte adherence to glass surfaces and/or degradation are avoided as extraction occurs in situ, while analytes are isolated from a complex matrix that contains degradation agents (bacteria, oxidizing or reducing species, etc.). This procedure also circumvents the splitting of original samples into sub-samples. The second approach involves the use of portable TFME devices that facilitate on-site extraction of compounds, therefore eliminating the use of collection vessels, a factor known to potentially introduce errors into analysis. The herein described procedure involves attachment of the TFME device to drill accessories, analyte extraction via direct immersion into sampled site, and subsequent on-site instrumental analysis, which is carried out with the use of a portable GC/MS containing an appropriate thermal desorption interface, or alternatively, by transferring the membrane to the laboratory for bench-top GC/MS analysis. To facilitate a better understanding of the processes governing the developed approaches, modeling by COMSOL Multiphysics® software was performed. The findings of this study were applied for further method optimization, and the optimized developed methods were then applied for on-site surface water analyses. Finally, the greenness of the developed methods was evaluated with use of the eco-scale assessment, with obtained scores compared to that of the US EPA 8270 method.Ontario Research FundMaxxam Analytics (Mississagua, ON

Exploiting the tunable selectivity features of polymeric ionic liquid-based SPME sorbents in food analysis

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.talanta.2018.06.011 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/In this work, the performances of polymeric ionic liquid (PIL) based solid-phase microextraction (SPME) coatings were assessed for applications concerning food safety and quality. Two different polymeric ionic liquid coatings, namely poly(1–4-vinylbenzyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl] imide (poly([VBHDIM][NTf2]), PIL 1, and N,N-didecyl-N-methyl-d-glucaminium poly(2-methyl-acrylic acid 2-[1-(3-{2-[2-(3-trifluoromethanesulfonylamino-propoxy)-ethoxy]-ethoxy}-propylamino)-vinylamino]-ethyl ester) (poly([DDMGlu][MTFSI]), PIL 2, were evaluated. The PIL-based coatings were compared to commercially available SPME coatings in terms of their performance toward extraction of pesticides and fruit metabolites. The partition coefficients (Kfs) of the tested coatings were calculated, with PIL 1 demonstrating similar or better performance compared to the commercial coatings. Design of experiment (DoE) was applied to optimize the parameters that most influenced SPME extraction, and a quantitative method for determination of 5 organophosphorus pesticides was developed by using PIL-based coatings and commercial SPME fibers. Despite the thin layer of the sorbent coating, PIL 1 achieved limits of quantitation at the low part-per-billion level. Moreover, in a comparative investigation of analyte coverage carried out via HS-SPME-GCxGC-ToF/MS with grape homogenate as model matrix, excellent performances were observed for the PIL-based coatings toward the determination of fruit metabolites, demonstrating their capability towards broad extractive coverage of analytes characterized by various physicochemical properties.Natural Sciences and Engineering Research Council of Canada ["IRCPJ 184412-15"]National Science Foundation ["CHE-1709372"]