Publications by authors named "Nicolas Drouin"

12 Publications

  • Page 1 of 1

Evaluation of a nanoflow interface based on the triple-tube coaxial sheath-flow sprayer for capillary electrophoresis-mass spectrometry coupling in metabolomics.

J Chromatogr A 2021 Feb 9;1641:461982. Epub 2021 Feb 9.

School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, Geneva, Switzerland; Swiss Centre for Applied Human Toxicology (SCAHT), Switzerland. Electronic address:

The performance of an original CE-MS interface that allows the in-axis positioning of the electrospray with respect to the MS inlet was evaluated. The variations in the geometrical alignment of this configuration in the absence of a nebulizing gas afforded a significant reduction in the sheath-liquid flow rate from 3 µL/min to as low as 300 nL/min. The sheath liquid and BGE were respectively composed of HO-iPrOHCHCOOH 50:50:1 (v/v/v) and 10% acetic acid (pH 2.2). A significant gain in sensitivity was obtained, and it was correlated to the effective mobility of the analytes. Compounds with low mobility values showed a greater sensitivity gain. Special attention was paid to the detection of proteinogenic amino acids. Linear response functions were obtained from 15 ng/mL to 500 ng/mL. The limits of quantification, as low as 34.3 ng/mL, were improved by a factor of up to six compared to the conventional configuration. The in-axis setup was ultimately applied to the absolute quantification of four important amino acids, alanine, tyrosine, methionine and valine, in standard reference material (NIST plasma). The accuracies ranged from 78 to 113%, thus demonstrating the potential of this configuration for metabolomics.
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http://dx.doi.org/10.1016/j.chroma.2021.461982DOI Listing
February 2021

A high-throughput, ultrafast, and online three-phase electro-extraction method for analysis of trace level pharmaceuticals.

Anal Chim Acta 2021 Mar 7;1149:338204. Epub 2021 Jan 7.

Analytical Biosciences and Metabolomics, Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, the Netherlands; Research Group Metabolomics, Leiden Center for Applied Bioscience, University of Applied Sciences Leiden, the Netherlands. Electronic address:

Sample preparation is often reported as the main bottleneck of analytical processes. To meet the requirements of both high-throughput and high sensitivity, improved sample-preparation methods capable of fast analyte preconcentration are urgently needed. To this end, a new three-phase electroextraction (EE) method is presented that allows for ultrafast electroextraction hyphenated to flow-injection analysis mass spectrometry (FIA-MS). Four model compounds, i.e., propranolol, amitriptyline, bupivacaine, and oxeladin, were used to optimize and evaluate the method. Within only 30 s extraction time, enrichment factors (EF) of 105-569 and extraction recoveries (ER) of 10.2%-55.7% were achieved for these analytes, with limits of detection (LODs) ranging from 0.36 to 3.21 ng mL, good linear response function (R > 0.99), low relative standard deviation (0.6%-17.8%) and acceptable accuracy (73-112%). Finally, the optimized three-phase EE method was successfully applied to human urine and plasma samples. Our three-phase electroextraction method is simple to construct and offers ultrafast, online extraction of trace amounts of analytes from biological samples, and therefore has great potential for high-throughput analysis.
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http://dx.doi.org/10.1016/j.aca.2021.338204DOI Listing
March 2021

Capillary Electrophoresis-Mass Spectrometry at Trial by Metabo-Ring: Effective Electrophoretic Mobility for Reproducible and Robust Compound Annotation.

Anal Chem 2020 10 1;92(20):14103-14112. Epub 2020 Oct 1.

Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, 2311 G Leiden, The Netherlands.

Capillary zone electrophoresis-mass spectrometry (CE-MS) is a mature analytical tool for the efficient profiling of (highly) polar and ionizable compounds. However, the use of CE-MS in comparison to other separation techniques remains underrepresented in metabolomics, as this analytical approach is still perceived as technically challenging and less reproducible, notably for migration time. The latter is key for a reliable comparison of metabolic profiles and for unknown biomarker identification that is complementary to high resolution MS/MS. In this work, we present the results of a Metabo-ring trial involving 16 CE-MS platforms among 13 different laboratories spanning two continents. The goal was to assess the reproducibility and identification capability of CE-MS by employing effective electrophoretic mobility (μ) as the key parameter in comparison to the relative migration time (RMT) approach. For this purpose, a representative cationic metabolite mixture in water, pretreated human plasma, and urine samples spiked with the same metabolite mixture were used and distributed for analysis by all laboratories. The μ was determined for all metabolites spiked into each sample. The background electrolyte (BGE) was prepared and employed by each participating lab following the same protocol. All other parameters (capillary, interface, injection volume, voltage ramp, temperature, capillary conditioning, and rinsing procedure, etc.) were left to the discretion of the contributing laboratories. The results revealed that the reproducibility of the μ for 20 out of the 21 model compounds was below 3.1% vs 10.9% for RMT, regardless of the huge heterogeneity in experimental conditions and platforms across the 13 laboratories. Overall, this Metabo-ring trial demonstrated that CE-MS is a viable and reproducible approach for metabolomics.
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http://dx.doi.org/10.1021/acs.analchem.0c03129DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581015PMC
October 2020

Evaluation of ion mobility in capillary electrophoresis coupled to mass spectrometry for the identification in metabolomics.

Electrophoresis 2021 Feb 6;42(4):342-349. Epub 2020 Sep 6.

Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, Geneva, Switzerland.

Currently, feature annotation remains one of the main challenges in untargeted metabolomics. In this context, the information provided by high-resolution mass spectrometry (HRMS) in addition to accurate mass can improve the quality of metabolite annotation, and MS/MS fragmentation patterns are widely used. Accurate mass and a separation index, such as retention time or effective mobility (μ ), in chromatographic and electrophoretic approaches, respectively, must be used for unequivocal metabolite identification. The possibility of measuring collision cross-section (CCS) values by using ion mobility (IM) is becoming increasingly popular in metabolomic studies thanks to the new generation of IM mass spectrometers. Based on their similar separation mechanisms involving electric field and the size of the compounds, the complementarity of CCS and μ needs to be evaluated. In this study, a comparison of CCS and μ was achieved in the context of feature identification ability in untargeted metabolomics by capillary zone electrophoresis (CZE) coupled with HRMS. This study confirms the high correlation of CCS with the mass of the studied metabolites as well as the orthogonality between accurate mass and μ , making this combination particularly interesting for the identification of several endogenous metabolites. The use of IM-MS remains of great interest for facilitating the annotation of neutral metabolites present in the electroosmotic flow (EOF) that are poorly or not separated by CZE.
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http://dx.doi.org/10.1002/elps.202000120DOI Listing
February 2021

Electromembrane Extraction of Highly Polar Compounds: Analysis of Cardiovascular Biomarkers in Plasma.

Metabolites 2019 Dec 18;10(1). Epub 2019 Dec 18.

Division of Systems Biomedicine and Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.

Cardiovascular diseases (CVDs) represent a major concern in today's society, with more than 17.5 million deaths reported annually worldwide. Recently, five metabolites related to the gut metabolism of phospholipids were identified as promising predictive biomarker candidates for CVD. Validation of those biomarker candidates is crucial for applications to the clinic, showing the need for high-throughput analysis of large numbers of samples. These five compounds, trimethylamine N-oxide (TMAO), choline, betaine, l-carnitine, and deoxy-l-carnitine (4-trimethylammoniobutanoic acid), are highly polar compounds and show poor retention on conventional reversed phase chromatography, which can lead to strong matrix effects when using mass spectrometry detection, especially when high-throughput analysis approaches are used with limited separation of analytes from interferences. In order to reduce the potential matrix effects, we propose a novel fast parallel electromembrane extraction (Pa-EME) method for the analysis of these metabolites in plasma samples. The evaluation of Pa-EME parameters was performed using multi segment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). Recoveries up to 100% were achieved, with variability as low as 2%. Overall, this study highlights the necessity of protein precipitation prior to EME for the extraction of highly polar compounds. The developed Pa-EME method was evaluated in terms of concentration range and response function, as well as matrix effects using fast-LC-MS/MS. Finally, the developed workflow was compared to conventional sample pre-treatment, i.e., protein precipitation using methanol, and fast-LC-MS/MS. Data show very strong correlations between both workflows, highlighting the great potential of Pa-EME for high-throughput biological applications.
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http://dx.doi.org/10.3390/metabo10010004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022788PMC
December 2019

Quantitative CE analysis of punicalagin in Combretum aculeatum extracts traditionally used in Senegal for the treatment of tuberculosis.

Electrophoresis 2019 11 20;40(21):2820-2827. Epub 2019 Sep 20.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.

Mycobacterium tuberculosis is the causative agent of tuberculosis, an infectious bacterial disease, which most commonly affects the lungs. In the search for novel active compounds or medicines against tuberculosis, an ethnopharmacological survey combined with a host-pathogen assay has recently highlighted the potency of an aqueous extract of Combretum aculeatum. C. aculeatum is used in traditional medicine and has demonstrated a significant in vitro antimycobacterial activity. Punicalagin, an ellagitannin, was isolated and found to be related to the biological activity of the extract. An analytical method for the evaluation of punicalagin in C. aculeatum was developed by capillary electrophoresis. After method optimization, the quantification of punicalagin was achieved for the evaluation of various plant extracts to determine the content of punicalagin related to the extraction modes and conditions, origin of the plant material, and harvesting period. The developed method demonstrated that the leaves presented the highest punicalagin content compared to the seeds and stems. A decoction of 30 min in boiling water was found to be the best extraction mode of C. aculeatum.
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http://dx.doi.org/10.1002/elps.201900240DOI Listing
November 2019

Effective mobility as a robust criterion for compound annotation and identification in metabolomics: Toward a mobility-based library.

Anal Chim Acta 2018 Nov 26;1032:178-187. Epub 2018 May 26.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Rue Michel Servet 1, 1211, Geneva 4, Switzerland. Electronic address:

Capillary electrophoresis (CE) presents many advantageous features as an analytical technique in metabolomics, such as very low consumption of a sample or the possibility to easily detect very polar and ionizable compounds. However, CE remains an approach only used by a few research groups due to a relatively lower sensitivity and, higher analysis time compared to liquid chromatography. To circumvent these drawbacks, herein we propose a generic CE-mass spectrometry (MS) approach using positive electrospray ionization mode and performing normal- and reverse-polarity CE separations to analyze anionic and acidic compounds. Preliminary experiments showed better sensitivity using the ESI positive mode compared to the ESI negative mode on a set of representative anionic compounds from different biochemical families. This approach was applied to the investigation of an available library of metabolites. More than 450 compounds out of the 596 in the library were detected, with the possibility to monitor negatively ionizable compounds through their ammonium adducts. Migration time of each data point was converted to an effective mobility (μ) scale and used for peak alignment in data pre-processing; μ features were used as a robust migration index for peak annotation and identification criterion. For the first time, a large database based on experimental μ was built, allowing for the straightforward annotation of detected features in biological samples and demonstrating how CE-MS can complement other analytical techniques commonly used in metabolomics.
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http://dx.doi.org/10.1016/j.aca.2018.05.063DOI Listing
November 2018

New supported liquid membrane for electromembrane extraction of polar basic endogenous metabolites.

J Pharm Biomed Anal 2018 Sep 20;159:53-59. Epub 2018 Jun 20.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland. Electronic address:

Extraction of polar endogenous compounds remains an important issue in bioanalysis although different techniques have been evaluated. Among them, electromembrane extraction (EME) is a relevant approach but supported liquid membranes (SLMs) dedicated to polar molecules are still lacking. In this study 22 organic solvents were evaluated as SLMs on a set of 45 polar basic metabolites (log P from -5.7 to 1.5) from various biochemical families. To investigate a large variety of organic solvents, a parallel electromembrane extraction device was used and a constant current approach was applied to circumvent the heterogeneous conductivities of the different SLMs. Among the tested organic solvents, 2-nitrophenyl pentyl ether (NPPE) appeared the most efficient SLM with the extraction of a large variety of polar cationic metabolites, high extraction yields, and low extraction variabilities. The applied current and the composition of the acceptor and donor solutions were also evaluated and 300 μA per well and acetic acid 1% (v/v), both as acceptor and donor compartments, were the most efficient conditions. The new SLM and the optimized experimental parameters were successfully applied to the extraction of precipitated plasma samples. Although the extraction recovery decreased for most compounds in the biological matrix, process efficiency (PE) up to 90% and low extraction variability (RSD between 2 and 18%) were obtained for several very polar compounds such as choline or acetylcholine, emphasizing the potential of EME for polar compounds.
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http://dx.doi.org/10.1016/j.jpba.2018.06.029DOI Listing
September 2018

ROMANCE: A new software tool to improve data robustness and feature identification in CE-MS metabolomics.

Electrophoresis 2018 05 24;39(9-10):1222-1232. Epub 2018 Jan 24.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.

The use of capillary electrophoresis coupled to mass spectrometry (CE-MS) in metabolomics remains an oddity compared to the widely adopted use of liquid chromatography. This technique is traditionally regarded as lacking the reproducibility to adequately identify metabolites by their migration times. The major reason is the variability of the velocity of the background electrolyte, mainly coming from shifts in the magnitude of the electroosmotic flow and from the suction caused by electrospray interfaces. The use of the effective electrophoretic mobility is one solution to overcome this issue as it is a characteristic feature of each compound. To date, such an approach has not been applied to metabolomics due to the complexity and size of CE-MS data obtained in such studies. In this paper, ROMANCE (RObust Metabolomic Analysis with Normalized CE) is introduced as a new software for CE-MS-based metabolomics. It allows the automated conversion of batches of CE-MS files with minimal user intervention. ROMANCE converts the x-axis of each MS file from the time into the effective mobility scale and the resulting files are already pseudo-aligned, present normalized peak areas and improved reproducibility, and can eventually follow existing metabolomic workflows. The software was developed in Scala, so it is multi-platform and computationally-efficient. It is available for download under a CC license. In this work, the versatility of ROMANCE was demonstrated by using data obtained in the same and in different laboratories, as well as its application to the analysis of human plasma samples.
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http://dx.doi.org/10.1002/elps.201700427DOI Listing
May 2018

Sample preparation for polar metabolites in bioanalysis.

Analyst 2017 Dec;143(1):16-20

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland.

Sample preparation is a primary step of any bioanalytical workflow, especially in metabolomics analysis where maximum information has to be obtained without spoiling the analytical instrument. Because of their biological implication, highly polar metabolites, such as amino acids, nucleobases, and catecholamines seem to attract growing interest in the field of comprehensive metabolomics analysis although their extraction from the matrix remains a real challenge. In this paper, we discuss about the actual practice and issues of hydrophilic metabolites' extraction, including new solutions and perspectives to improve their phase transfer from a complex biological sample to a clean extract prior to analysis.
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http://dx.doi.org/10.1039/c7an01333gDOI Listing
December 2017

Development of a New Extraction Device Based on Parallel-Electromembrane Extraction.

Anal Chem 2017 06 8;89(12):6346-6350. Epub 2017 Jun 8.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne , 1 Rue Michel-Servet 1211 Geneva 4, Switzerland.

A new device for parallel-electromembrane extraction (Pa-EME) was developed to enable simultaneous and high-throughput extraction of ionic and ionizable compounds from biofluids. The new system is composed of a reusable conductive well-plate used as an acceptor compartment and a filtration well-plate used as a donor compartment. A design of experiments was implemented to optimize the main experimental parameters (agitation, voltage, and time) with standard solutions in formic acid 50 mM. The stirring rate was found the primary influent parameter. The Pa-EME device showed excellent extraction yields from 84% to 101% with RSD lower than 7.5% on model compounds. Optimized parameters were then applied to plasma samples and process efficiencies from 59% to 62% and RSD of less than 8.0% were obtained. The whole extraction process took less than 20 min to prepare 8 samples simultaneously, greatly enhancing the sample preparation throughput (<3 min per sample).
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http://dx.doi.org/10.1021/acs.analchem.7b01284DOI Listing
June 2017

Dynamic-Electromembrane Extraction: A Technical Development for the Extraction of Neuropeptides.

Anal Chem 2016 05 26;88(10):5308-15. Epub 2016 Apr 26.

School of Pharmaceutical Sciences, University of Geneva, University of Lausanne , Boulevard d'Yvoy 20, 1211 Geneva 4, Switzerland.

In this work, a dynamic-electromembrane extraction (d-EME) device was developed for the extraction of neuropeptides. On the basis of a thin polypropylene hollow fiber (50 μm of wall-thickness and 280 μm i.d.), this setup allowed for a continual renewal of the acceptor compartment. Because of the reduced size of the device, high preconcentration factors were obtained (up to 50-fold). The extraction remained constant regardless of the extraction time (from 15 to 45 min); accordingly, this new setup minimized the effect of electrolysis on extraction performance while enabling high extraction yield (up to 72%) for most lipophilic neuropeptides.
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http://dx.doi.org/10.1021/acs.analchem.6b00559DOI Listing
May 2016