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Author Van Echelpoel, R.; Parrilla, M.; Sleegers, N.; Thiruvottriyur Shanmugam, S.; van Nuijs, A.L.N.; Slosse, A.; Van Durme, F.; De Wael, K. pdf  url
doi  openurl
  Title Validated portable device for the qualitative and quantitative electrochemical detection of MDMA ready for on-site use Type A1 Journal article
  Year (down) 2023 Publication Microchemical journal Abbreviated Journal  
  Volume 190 Issue Pages 108693-10  
  Keywords A1 Journal article; Engineering sciences. Technology; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract Identifying and quantifying 3,4-methyl​enedioxy​methamphetamine (MDMA) on-site in suspected illicit drug samples, whether it be at recreational settings or manufacturing sites, is a major challenge for law enforcement agencies (LEAs). Various analytical techniques exist to fulfil this goal, e.g. colourimetry and portable spectroscopic techniques, each having its specific limitations (e.g. low accuracy, fluorescence, no quantification) and strengths (e.g. fast, easy to use). In this work, for the first time, an electrochemical MDMA sensor is presented to become a detection tool that can realistically be used on-site. More specifically, the use of a single buffer solution and an unmodified screen-printed electrode, along with the integration of a data analysis algorithm and mobile application permits the straightforward on-site identification and quantification of MDMA in suspicious samples. Multiple studies investigating different parameters, including pH, concentration, reproducibility, temperature and binary mixture analyses, were executed. To fully understand all the occurring redox processes, liquid chromatography coupled with high-resolution mass spectrometry analysis of partially electrolyzed MDMA samples was performed unravelling oxidation of the methylenedioxy group. Validation of the methodology was executed on 15 MDMA street samples analysed by gas chromatography coupled with mass spectrometry and compared with the performance of a commercial portable Raman and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) device. The novel methodology outperformed the spectroscopic techniques, correctly identifying all 15 street samples. Additionally, the electrochemical sensor predicted the purity of the tablets with a mean absolute error of 2.3%. Overall, this new, electrochemical detection strategy provides LEAs the rapid, low-cost, on-site detection and quantification of MDMA in suspicious samples, without requiring specialized training.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000977060400001 Publication Date 2023-03-31  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0026-265x; 0026-265x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 4.8 Times cited Open Access OpenAccess  
  Notes Approved Most recent IF: 4.8; 2023 IF: 3.034  
  Call Number UA @ admin @ c:irua:195415 Serial 8952  
Permanent link to this record
 

 
Author Drăgan, A.-M.; Parrilla, M.; Sleegers, N.; Slosse, A.; Van Durme, F.; van Nuijs, A.; Oprean, R.; Cristea, C.; De Wael, K. pdf  doi
openurl 
  Title Investigating the electrochemical profile of methamphetamine to enable fast on-site detection in forensic analysis Type A1 Journal article
  Year (down) 2023 Publication Talanta : the international journal of pure and applied analytical chemistry Abbreviated Journal  
  Volume 255 Issue Pages 124208-124211  
  Keywords A1 Journal article; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract Methamphetamine (MA) is a synthetic psychoactive drug which is consumed both licitly and illicitly. In some countries it is prescribed for attention-deficit and hyperactivity disorder, and short-term treatment of obesity. More often though, it is abused for its psychostimulant properties. Unfortunately, the spread and abuse of this synthetic drug have increased globally, being reported as the most widely consumed synthetic psychoactive drug in the world in 2019. Attempting to overcome the shortcomings of the currently used on-site methods for MA detection in suspected cargos, the present study explores the potential of electrochemical identification of MA by means of square wave voltammetry on disposable graphite screen-printed electrodes. Hence, the analytical characterization of the method was evaluated under optimal conditions exhibiting a linear range between 50 mu M and 2.5 mM MA, a LOD of 16.7 mu M, a LOQ of 50.0 mu M and a sensitivity of 5.3 mu A mM-1. Interestingly, two zones in the potential window were identified for the detection of MA, depending on its concentration in solution. Furthermore, the oxidative pathway of MA was elucidated employing liquid chromatography – mass spectrometry to understand the change in the electrochemical profile. Thereafter, the selectivity of the method towards MA in mixtures with other drugs of abuse as well as common adulterants/cutting agents was evaluated. Finally, the described method was employed for the analysis of MA in confiscated samples and compared with forensic methods, displaying its potential as a fast and easy-to-use method for on-site analysis.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000925076200001 Publication Date 2023-01-05  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0039-9140; 1873-3573 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.1 Times cited Open Access Not_Open_Access  
  Notes Approved Most recent IF: 6.1; 2023 IF: 4.162  
  Call Number UA @ admin @ c:irua:194314 Serial 8890  
Permanent link to this record
 

 
Author Montiel, F.N.; Parrilla, M.; Sleegers, N.; Van Durme, F.; van Nuijs, A.L.N.; De Wael, K. pdf  url
doi  openurl
  Title Electrochemical sensing of amphetamine-type stimulants (pre)-precursors to fight against the illicit production of synthetic drugs Type A1 Journal article
  Year (down) 2022 Publication Electrochimica acta Abbreviated Journal  
  Volume 436 Issue Pages 141446-11  
  Keywords A1 Journal article; Engineering sciences. Technology; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract The illicit drug precursor market for the manufacture of amphetamine-type stimulants (ATS), mainly amphetamine, methamphetamine and methylenedioxymethamphetamine (MDMA), has emerged quickly in the last years. The evidence of a more complex and sophisticated drug market underlines the pressing need for new on-site methods to quickly detect precursors of synthetic drugs, with electrochemical analysis as a promising technique. Herein, the electrochemical fingerprints of ten common ATS precursors-3-oxo-2-phenylbutanenitrile (APAAN), 3-oxo-2-phenylbutanamide (APAA), methyl 3-oxo-2-phenylbutanoate (MAPA), benzyl methyl ketone (BMK), 1-(1,3-benzodioxol-5-yl)propan-2-one (PMK), ephedrine, pseudoephedrine, safrole, sassafras oil and piperonal- are reported for the first time. The electrochemical screening disclosed the redox inactivity of BMK, which is an essential starting material for the production of ATS. Therefore, the local derivatization of BMK at an electrode surface by reductive amination is presented as a feasible solution to enrich its electrochemical fingerprint. To prove that, the resulting mixture was analyzed using a set of chromatographic techniques to understand the reaction mechanism and to identify possible electrochemical active products. Two reaction products (i.e. methamphetamine and 1-phenylpropan-2-ol) were found and characterized using mass spectrometry and electrochemical methods. Subsequently, the optimization of the reaction parameters was carefully addressed to set the portable electrochemical sensing strategy. Ultimately, the analysis concept was validated for the qualitative identification of ATS precursors in seizures from a forensic institute. Overall, the electrochemical approach demonstrates to be a useful and affordable analytical tool for the early identification of ATS precursors to prevent trafficking and drug manufacture in clandestine laboratories.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000914833800003 Publication Date 2022-10-27  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0013-4686 ISBN Additional Links UA library record; WoS full record  
  Impact Factor Times cited Open Access OpenAccess  
  Notes Approved no  
  Call Number UA @ admin @ c:irua:191622 Serial 8858  
Permanent link to this record
 

 
Author Neven, L.; Barich, H.; Sleegers, N.; Cánovas, R.; Debruyne, G.; De Wael, K. pdf  url
doi  openurl
  Title Development of a combi-electrosensor for the detection of phenol by combining photoelectrochemistry and square wave voltammetry Type A1 Journal article
  Year (down) 2022 Publication Analytica chimica acta Abbreviated Journal  
  Volume 1206 Issue Pages 339732  
  Keywords A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract The high toxicity, endocrine-disrupting effects and low (bio)degradability commonly attributed to phenolic compounds have promoted their recognition as priority toxic pollutants. For this reason, the monitoring of these compounds in industrial, domestic and agricultural streams is crucial to prevent and decrease their toxicity in our daily life. To confront this relevant environmental issue, we propose the use of a combi-electrosensor which combines singlet oxygen (1O2)-based photoelectrochemistry (PEC) with square wave voltammetry (SWV). The high sensitivity of the PEC sensor (being a faster alternative for traditional COD measurements) ensures the detection of nmol L−1 levels of phenolic compounds while the SWV measurements (being faster than the color test kits) allow the differentiation between phenolic compounds. Herein, we report on the development of such a combi-electrosensor for the sensitive and selective detection of phenol (PHOH) in the presence of related phenolic compounds such as hydroquinone (HQ), bisphenol A (BPA), resorcinol (RC) and catechol (CC). The PEC sensor was able to determine the concentration of PHOH in spiked river samples containing only PHOH with a recovery between 96% and 111%. The SWV measurements elucidated the presence of PHOH, HQ and CC in the spiked samples containing multiple phenol compounds. Finally, the practicality of the combi-electrosensor set-up with a dual SPE containing two working electrodes and shared reference and counter electrodes was demonstrated. As a result, the combination of the two techniques is a powerful and valuable tool in the analysis of phenolic samples, since each technique improves the general performance by overcoming the inherent drawbacks that they display independently.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000793070200016 Publication Date 2022-03-16  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2670; 1873-4324 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor Times cited Open Access OpenAccess  
  Notes Approved no  
  Call Number UA @ admin @ c:irua:187499 Serial 8848  
Permanent link to this record
 

 
Author Schram, J.; Parrilla, M.; Sleegers, N.; Van Durme, F.; van den Berg, J.; van Nuijs, A.L.N.; De Wael, K. pdf  url
doi  openurl
  Title Electrochemical profiling and liquid chromatography–mass spectrometry characterization of synthetic cathinones : from methodology to detection in forensic samples Type A1 Journal article
  Year (down) 2021 Publication Drug Testing And Analysis Abbreviated Journal Drug Test Anal  
  Volume 13 Issue 7 Pages 1282-1294  
  Keywords A1 Journal article; Pharmacology. Therapy; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract The emergence of new psychoactive drugs in the market demands rapid and accurate tools for the on‐site classification of illegal and legal compounds with similar structures. Herein, a novel method for the classification of synthetic cathinones (SC) is presented based on their electrochemical profile. First, the electrochemical profile of five common SC (i.e., mephedrone, ethcathinone, methylone, butylone and 4‐chloro‐alpha‐pyrrolidinovalerophenone) is collected to build calibration curves using square wave voltammetry on graphite screen‐printed electrodes (SPE). Second, the elucidation of the oxidation pathways, obtained by liquid chromatography‐high resolution mass spectrometry, allows the pairing of the oxidation products to the SC electrochemical profile, providing a selective and robust classification. Additionally, the effect of common adulterants and illicit drugs on the electrochemical profile of the SC is explored. Interestingly, a cathodic pretreatment of the SPE allows the selective detection of each SC in presence of electroactive adulterants. Finally, the electrochemical approach is validated with gas‐chromatography‐mass spectrometry by analyzing 26 confiscated samples from seizures and illegal webshops. Overall, the electrochemical method exhibits a successful classification of SC including structural derivatives, a crucial attribute in an ever‐diversifying drug market.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000624902500001 Publication Date 2021-02-24  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1942-7603; 1942-7611 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 3.469 Times cited Open Access OpenAccess  
  Notes Approved Most recent IF: 3.469  
  Call Number UA @ admin @ c:irua:175583 Serial 7863  
Permanent link to this record
 

 
Author Sleegers, N.; van Nuijs, A.L.N.; van den Berg, M.; De Wael, K. pdf  doi
openurl 
  Title Electrochemistry of intact versus degraded cephalosporin antibiotics facilitated by LC–MS analysis Type A1 Journal article
  Year (down) 2021 Publication Analytical Chemistry Abbreviated Journal Anal Chem  
  Volume 93 Issue 4 Pages 2394-2402  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract The electrochemical detection of cephalosporins is a promising approach for the monitoring of cephalosporin levels in process waters. However, this class of antibiotics, like penicillins, is composed of chemically active molecules and susceptible to hydrolysis and aminolysis of the four membered β-lactam ring present. In order to develop a smart monitoring strategy for cephalosporins, the influence of degradation (hydrolysis and aminolysis) on the electrochemical fingerprint has to be taken into account. Therefore, an investigation was carried out to understand the changes of the voltammetric fingerprints upon acidic and alkaline degradation. Changes in fingerprints were correlated to the degradation pathways through the combination of square wave voltammetry and liquid chromatography quadrupole time-of-flight analysis. The characteristic electrochemical signals of the β-lactam ring disappeared upon hydrolysis. Additional oxidation signals that appeared after degradation were elucidated and linked to different degradation products, and therefore, enrich the voltammetric fingerprints with information of the state of the cephalosporins. The applicability of the electrochemical monitoring system was explored by the analysis of the intact and degraded industrial process waters containing the key intermediate 7-aminodeacetoxycephalosporanic acid (7-ADCA). Clearly, the intact process samples exhibited the expected core signals of 7-ADCA and could be quantified, while the degraded samples only showed the newly formed degradation products.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000618089100063 Publication Date 2021-01-04  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700; 5206-882x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.32 Times cited Open Access Not_Open_Access  
  Notes Approved Most recent IF: 6.32  
  Call Number UA @ admin @ c:irua:176206 Serial 7864  
Permanent link to this record
 

 
Author Schram, J.; Thiruvottriyur Shanmugam, S.; Sleegers, N.; Florea, A.; Samyn, N.; van Nuijs, A.L.N.; De Wael, K. pdf  doi
openurl 
  Title Local conversion of redox inactive molecules into redox active ones : a formaldehyde based strategy for the electrochemical detection of illicit drugs containing primary and secondary amines Type A1 Journal article
  Year (down) 2021 Publication Electrochimica Acta Abbreviated Journal Electrochim Acta  
  Volume 367 Issue Pages 137515  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract Electrochemical techniques have evidenced to be highly suitable for the development of portable, rapid and accurate screening methods for the detection of illicit drugs in seized samples. However, the redox inactivity of primary amines, one of the most common functional groups of illicit drugs, masks voltammetric detection in aqueous environment at carbon electrodes and, therefore, leads to false negative results if only these primary amines are present in the structures. This work explores the feasibility of a derivatisation approach that introduces formaldehyde in the measuring conditions in order to achieve methylation, via an Eschweiler-Clarke mechanism, of illicit drugs containing primary and secondary amines, using amphetamine (AMP) and methamphetamine (MET) as model molecules. As a result the electrochemical fingerprint is enriched and thereby the detectability enhanced. A combination of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOFMS) and square-wave voltammetric (SWV) measurements is employed to identify reaction products and link them to the observed redox peaks. Although an alkaline environment (pH 12.0) proved to increase the reaction yield, a richer electrochemical fingerprint (EF) is obtained in neutral conditions (pH 7.0). Similarly, the addition of formate improved the reaction conversion but reduced the EF by eliminating a redox peak that is attributed to side products formed in the absence of formate. To illustrate the applicability, the derivatisation strategy is applied to several prominent illicit drugs containing primary and secondary amines to demonstrate its EF enriching capabilities. Finally, real street samples from forensic seizures are analysed. Overall, this strategy unlocks the detectability of the hitherto undetectable AMP and other drugs only containing primary amines, while strongly facilitating the identification of MET and analogues. These findings are not limited to illicit drugs, the insights can ultimately be applied to other target molecules containing similar functional groups. (C) 2020 Published by Elsevier Ltd.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000607620700010 Publication Date 2020-11-21  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0013-4686 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 4.798 Times cited Open Access Not_Open_Access  
  Notes Approved Most recent IF: 4.798  
  Call Number UA @ admin @ c:irua:176083 Serial 8177  
Permanent link to this record
 

 
Author Sleegers, N. openurl 
  Title Cephalosporin antibiotics : electrochemical fingerprints and redox pathways investigated by mass spectral analysis Type Doctoral thesis
  Year (down) 2021 Publication Abbreviated Journal  
  Volume Issue Pages 208 p.  
  Keywords Doctoral thesis; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos Publication Date  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Additional Links UA library record  
  Impact Factor Times cited Open Access  
  Notes Approved Most recent IF: NA  
  Call Number UA @ admin @ c:irua:181014 Serial 7588  
Permanent link to this record
 

 
Author de Jong, M.; Sleegers, N.; Schram, J.; Daems, D.; Florea, A.; De Wael, K. pdf  url
doi  openurl
  Title A Benzocaine‐Induced Local Near‐Surface pH Effect: Influence on the Accuracy of Voltammetric Cocaine Detection Type A1 Journal article
  Year (down) 2020 Publication Analysis & Sensing Abbreviated Journal Anal. Sens.  
  Volume Issue Pages anse.202000012  
  Keywords A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)  
  Abstract This work reports on a local induced near-surface pH effect (pHS), due to the presence of one analyte, leading to an influence or even suppression of redox signals of a second analyte present in solution. This concept and its impact on voltammetric sensing is illustrated by focusing on the detection of cocaine in the presence of the common adulterant benzocaine. An in-depth study on the occurring interference mechanism and why it occurs for benzocaine specifically and not for other adulterants was performed through the use of multiple electrochemical strategies. It was concluded that the potential shift and loss of intensity of the squarewave voltammetric cocaine signal in the presence of benzocaine was caused by a local pHS effect. A cathodic pretreatment strategy was developed to nonetheless allow accurate cocaine detection. The gathered insights are useful to explain unidentified phenomena involving compounds with properties similar to benzocaine in voltammetric electroanalysis.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos Publication Date 2020-10-20  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2629-2742 ISBN Additional Links UA library record  
  Impact Factor Times cited Open Access  
  Notes The authors acknowledge financial support from IOF-SBO/POC (UAntwerp), the Fund for Scientific Research (FWO) Flanders, Grant 1S 37658 17N and Grant 1SB 8120N, and VLAIO IM [HBC.2019.2181]. Approved Most recent IF: NA  
  Call Number AXES @ axes @c:irua:173031 Serial 6427  
Permanent link to this record
 

 
Author Schram, J.; Parrilla, M.; Sleegers, N.; Samyn, N.; Bijvoets, S.M.; Heerschop, M.W.J.; van Nuijs, A.L.N.; De Wael, K. pdf  doi
openurl 
  Title Identifying Electrochemical Fingerprints of Ketamine with Voltammetry and Liquid Chromatography–Mass Spectrometry for Its Detection in Seized Samples Type A1 Journal article
  Year (down) 2020 Publication Analytical Chemistry Abbreviated Journal Anal Chem  
  Volume 92 Issue 19 Pages 13485-13492  
  Keywords A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract Herein, a straightforward electrochemical approach for the determination of ketamine in street samples and seizures is presented by employing screen-printed electrodes (SPE). Square wave voltammetry (SWV) is used to study the electrochemical behavior of the illicit drug, thus profiling the different oxidation states of the substance at different pHs. Besides, the oxidation pathway of ketamine on SPE is investigated for the first time with liquid chromatography–high-resolution mass spectrometry. Under the optimized conditions, the calibration curve of ketamine at buffer solution (pH 12) exhibits a sensitivity of 8.2 μA μM–1, a linear relationship between 50 and 2500 μM with excellent reproducibility (RSD = 2.2%, at 500 μM, n = 7), and a limit of detection (LOD) of 11.7 μM. Subsequently, binary mixtures of ketamine with adulterants and illicit drugs are analyzed with SWV to investigate the electrochemical fingerprint. Moreover, the profile overlapping between different substances is addressed by the introduction of an electrode pretreatment and the integration of a tailor-made script for data treatment. Finally, the approach is tested on street samples from forensic seizures. Overall, this system allows for the on-site identification of ketamine by law enforcement agents in an easy-to-use and rapid manner on cargos and seizures, thereby disrupting the distribution channel and avoiding the illicit drug reaching the end-user.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000580426800091 Publication Date 2020-10-06  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 7.4 Times cited Open Access  
  Notes Universiteit Antwerpen; H2020 Societal Challenges, 833787 ; Fonds Wetenschappelijk Onderzoek, 1S3765817N 1SB8120N ; Approved Most recent IF: 7.4; 2020 IF: 6.32  
  Call Number AXES @ axes @c:irua:170523 Serial 6435  
Permanent link to this record
 

 
Author De Jong, M.; Sleegers, N.; Florea, A.; Van Loon, J.; van Nuijs, A.L.N.; Samyn, N.; De Wael, K. url  doi
openurl 
  Title Unraveling the mechanisms behind the complete suppression of cocaine electrochemical signals by chlorpromazine, promethazine, procaine, and dextromethorphan Type A1 Journal article
  Year (down) 2019 Publication Analytical chemistry Abbreviated Journal Anal Chem  
  Volume 91 Issue 24 Pages 15453-15460  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre; Product development  
  Abstract The present work investigates the challenges accompanied by the electrochemical cocaine detection in physiological conditions (pH 7) in the presence of chlorpromazine, promethazine, procaine, and dextromethorphan, frequently used cutting agents in cocaine street samples. The problem translates into the absence of the cocaine oxidation signal (signal suppression) when in a mixture with one of these compounds, leading to false negative results. Although a solution to this problem was provided through earlier experiments of our group, the mechanisms behind the suppression are now fundamentally investigated via electrochemical and liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) strategies. The latter was used to confirm the passivation of the electrodes due to their interaction with promethazine and chlorpromazine. Electron transfer mechanisms were further identified via linear sweep voltammetry. Next, adsorption experiments were performed on the graphite screen printed electrodes both with and without potential assistance in order to confirm if the suppression of the cocaine signals is due to passivation induced by the cutting agents or their oxidized products. The proposed strategies allowed us to identify the mechanisms of cocaine suppression for each cutting agent mentioned. Suppression due to procaine and dextromethorphan is caused by fouling of the electrode surface by their oxidized forms, while for chlorpromazine and promethazine the suppression of the cocaine signal is related to the strong adsorption of these (nonoxidized) cutting agents onto the graphite electrode surface. These findings provide fundamental insights in possible suppression and other interfering mechanisms using electrochemistry in general not only in the drug detection sector.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000503910600018 Publication Date 2019-11-14  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700; 5206-882x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.32 Times cited Open Access  
  Notes ; The authors acknowledge financial support from IOF-SBO/POC (UAntwerp) and the Fund for Scientific Research (FWO) Flanders, Grant 1S 37658 17N. ; Approved Most recent IF: 6.32  
  Call Number UA @ admin @ c:irua:165727 Serial 5887  
Permanent link to this record
 

 
Author Bottari, F.; Moro, G.; Sleegers, N.; Florea, A.; Cowen, T.; Piletsky, S.; van Nuijs, A.L.N.; De Wael, K. pdf  doi
openurl 
  Title Electropolymerized o-phenylenediamine on graphite promoting the electrochemical detection of nafcillin Type A1 Journal article
  Year (down) 2019 Publication Electroanalysis Abbreviated Journal Electroanal  
  Volume 32 Issue 32 Pages 135-141  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract By combining molecular modelling and electrochemistry we envision the creation of modified electrodes tailored for a more sensitive and selective detection of a single analyte. In this study we report on a graphite screen printed electrode modified with electropolymerized o-phenylenediamine, selected by rational design, which promotes the detection of nafcillin (NAF), an antibiotic. Parameters such as monomer concentration, pH and number of electropolymerization cycles were optimized to obtain the highest current signal for the target upon amperometric detection. NAF identification was based on the redox process at +1.1 V (vs pseudo Ag), ascribed to the oxidation of the C-7 side chain. With the optimized modification protocol, a two-fold increase in nafcillin signal could be obtained: the calibration plot in 0.1 M Britton-Robinson buffer pH 4 showed a limit of detection of 80 nM with improved sensitivity and reproducibility (RSD<5 %) compared to the detection at non-modified electrodes.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000482596300001 Publication Date 2019-08-26  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1040-0397 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 2.851 Times cited 1 Open Access  
  Notes ; FB and GM devised the study and performed the experiments, FB wrote the original draft of the paper and analysed the data, NS and AvN performed the MS experiments, AF helped with the optimization of the protocol and correction of the first draft, TC and SP performed the rational monomer design, KdW supervised the work and corrected the final draft. All authors gave their suggestions and corrections to the final version of the paper. This work was financially supported by the University of Antwerp (BOF) and the Research Foundation Flanders (FWO). ; Approved Most recent IF: 2.851  
  Call Number UA @ admin @ c:irua:162870 Serial 5601  
Permanent link to this record
 

 
Author Moro, G.; Bottari, F.; Sleegers, N.; Florea, A.; Cowen, T.; Moretto, L.M.; Piletsky, S.; De Wael, K. pdf  doi
openurl 
  Title Conductive imprinted polymers for the direct electrochemical detection of beta-lactam antibiotics: The case of cefquinome Type A1 Journal article
  Year (down) 2019 Publication Sensors and actuators : B : chemical Abbreviated Journal Sensor Actuat B-Chem  
  Volume 297 Issue 297 Pages 126786  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)  
  Abstract A biomimetic sensor for cefquinome (CFQ) was designed at multi-walled carbon nanotubes modified graphite screen-printed electrodes (MWCNTs-G-SPEs) as a proof-of-concept for the creation of a sensors array for beta-lactam antibiotics detection in milk. The sensitive and selective detection of antibiotic residues in food and environment is a fundamental step in the elaboration of prevention strategies to fight the insurgence of antimicrobial resistance (AMR) as recommended by authorities around the world (EU, WHO, FDA). The detection strategy is based on the characteristic electrochemical fingerprint of the target antibiotic cefquinome. A conducive electropolymerized molecularly imprinted polymer (MIP) coupled with MWCNTs was found to be the optimal electrode modifier, able to provide an increased selectivity and sensitivity for CFQ detection. The design of CFQ-MIP was facilitated by the rational selection of the monomer, 4-aminobenzoic acid (4-ABA). The electropolymerization process of 4-ABA have not been fully elucidated yet; for this reason a thorough study and optimization of electropolymerization conditions was performed to obtain a conducive and stable poly(4-ABA) film. The modified electrodes were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and cyclic voltammetry (CV). CFQ-MIP were synthesized at MWCNT-G-SPEs by electropolyrnerization in pH approximate to 1 (0.1 M sulphuric acid) with a monomer:template ratio of 5:1. Two different analytical protocols were tested (single and double step detection) to minimize unspecific adsorptions and improve the sensitivity. Under optimal conditions, the lowest CFQ concentration detectable by square wave voltammetry (SWV) at the modified sensor was 50 nM in 0.1 M phosphate buffer pH 2.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000478562700020 Publication Date 2019-07-08  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0925-4005 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 5.401 Times cited 4 Open Access  
  Notes ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 753223. This work was also supported by FWO. ; Approved Most recent IF: 5.401  
  Call Number UA @ admin @ c:irua:161777 Serial 5549  
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Author Neven, L.; Thiruvottriyur Shanmugam, S.; Rahemi, V.; Trashin, S.; Sleegers, N.; Carrion, E.N.; Gorun, S.M.; De Wael, K. pdf  url
doi  openurl
  Title Optimized photoelectrochemical detection of essential drugs bearing phenolic groups Type A1 Journal article
  Year (down) 2019 Publication Analytical chemistry Abbreviated Journal Anal Chem  
  Volume 91 Issue 15 Pages 9962-9969  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)  
  Abstract The World Health Organization (WHO) model “List of Essential Medicines” includes among indispensable medicines antibacterials and pain and migraine relievers. Monitoring their concentration in the environment, while challenging, is important in the context of antibiotic resistance as well as their production of highly toxic compounds via hydrolysis. Traditional detection methods such as high-performance liquid chromatography (HPLC) or LC combined with tandem mass spectrometry or UV-vis spectroscopy are time-consuming, have a high cost, require skilled operators and are difficult to adapt for field operations. In contrast, (electrochemical) sensors have elicited interest because of their rapid response, high selectivity, and sensitivity as well as potential for on-site detection. Previously, we reported a novel sensor system based on a type II photosensitizer, which combines the advantages of enzymatic sensors (high sensitivity) and photoelectrochemical sensors (easy baseline subtraction). Under red-light illumination, the photosensitizer produces singlet oxygen which oxidizes phenolic compounds present in the sample. The subsequent reduction of the oxidized phenolic compounds at the electrode surface gives rise to a quantifiable photocurrent and leads to the generation of a redox cycle. Herein we report the optimization in terms of pH and applied potential of the photoelectrochemical detection of the hydrolysis product of paracetamol, i.e., 4-aminophenol (4-AP), and two antibacterials, namely, cefadroxil (CFD, beta-lactam antibiotic) and doxycycline (DXC, tetracycline antibiotic). The optimized conditions resulted in a detection limit of 0.2 mu mol L-1 for DXC, but in a 10 times higher sensitivity, 20 nmol L-1, for CFD. An even higher sensitivity, 7 nmol L-1, was noted for 4-AP.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000480499200086 Publication Date 2019-06-25  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700; 5206-882x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.32 Times cited 2 Open Access  
  Notes ; FWO and UA-BOF are acknowledged for financial support. The Center for Functional Materials of Seton Hall University is thanked for support (S.M.G. and E.N.C.). Joren Van Loon is thanked for the graphical abstract. This research was supported by the medium scale research infrastructure funding Hercules funding (SEM). ; Approved Most recent IF: 6.32  
  Call Number UA @ admin @ c:irua:161831 Serial 5763  
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Author Sleegers, N.; van Nuijs, A.L.N.; van den Berg, M.; De Wael, K. url  doi
openurl 
  Title Cephalosporin antibiotics : electrochemical fingerprints and core structure reactions investigated by LC-MSMS Type A1 Journal article
  Year (down) 2019 Publication Analytical chemistry Abbreviated Journal Anal Chem  
  Volume 91 Issue 3 Pages 2035-2041  
  Keywords A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre  
  Abstract Electrochemistry and exploiting electrochemical fingerprints is a potent approach to address newly emerging surveillance needs, for instance for antibiotics. However, a comprehensive insight in the electrochemical oxidation behaviour and mechanism is re-quired for this sensing strategy. To address the lack in knowledge of the voltammetric behaviour of the cephalosporins antibiotics, a selection of cephalosporin antibiotics and two main intermediates were subjected to an electrochemical study of their redox behaviour by means of pulsed voltammetric techniques and small-scale electrolysis combined with HPLC-MS/MS analyses. Sur-prisingly, the detected oxidation products did not fit the earlier suggested oxidation of the sulfur group to the corresponding sul-foxide. The influence of different side chains, both at the three and the seven position of the β-lactam core structure on the elec-trochemical fingerprint were investigated. Additional oxidation signals at lower potentials were elucidated and linked to different side chains. These signals were further exploited to allow simultaneous detection of different cephalosporins in one voltammetric sweep. These fundamental insights can become the building blocks for an new on-site screening method.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000458220300055 Publication Date 2019-01-03  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700; 5206-882x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.32 Times cited 6 Open Access  
  Notes ; The authors acknowledge financial support from the Fund for Scientific Research (FWO) Flanders, Grant 1S 37658 17N. ; Approved Most recent IF: 6.32  
  Call Number UA @ admin @ c:irua:156046 Serial 5497  
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Author De Jong, M.; Sleegers, N.; Kim, J.; Van Durme, F.; Samyn, N.; Wang, J.; De Wael, K. url  doi
openurl 
  Title Electrochemical fingerprint of street samples for fast on-site screening of cocaine in seized drug powders Type A1 Journal article
  Year (down) 2016 Publication Chemical science Abbreviated Journal Chem Sci  
  Volume Issue Pages 1-7  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)  
  Abstract We report on a wearable fingertip sensor for on-the-spot identification of cocaine and its cutting agents in street samples. Traditionally, on-site screening is performed by means of colour tests which are difficult to interpret and lack selectivity. By presenting the distinct voltammetric response of cocaine, cutting agents, binary mixtures of cocaine and street samples in solution and powder street samples, we were able to elucidate the electrochemical fingerprint of all these compounds. The new electrochemical concept holds considerable promise as an on-site screening method.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000371021900094 Publication Date 2016-01-06  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2041-6520 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 8.668 Times cited 37 Open Access  
  Notes ; The authors acknowledge BELSPO for funding the APTADRU project (BR/314/PI/ APTADRU). ; Approved Most recent IF: 8.668  
  Call Number UA @ admin @ c:irua:130404 Serial 5591  
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