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“Trace analysis of estuarine brown algae by energy-dispersive X-ray fluorescence”. Sauter L, Van der Ben D, Van Grieken R, X-ray spectrometry 8, 159 (1979). http://doi.org/10.1002/XRS.1300080405
Abstract: Brown algae, which are good indicators for estuarine metal pollution, can advantageously be analysed by energy-dispersive X-ray fluorescence. The use of thin film samples and samples of intermediate thickness has several advantages over the conventional thick pellet procedure. A quite homogeneous thin target is prepared by suspending 15 mg of dried and ground seaweed powder in bi-distilled water and evaporating the slurry on a 10 cm2 Mylar foil held in a Teflon ring. The effective sample weight in the beam is calculated by a procedure based on the scatter peaks in the spectrum. Sensitivities are typically in the 215 ppm range. The coefficient of variation per analysis averaged over ten elements amounts to 10%. The natural concentration variation in seaweed specimens at one location is 13%. Samples from locations in the more polluted western Scheldt estuary yield significantly higher values for several elements, relative to the eastern Scheldt sites. Possible trace element variations between the top and base of plants, and between different seaweed specimens and sampling seasons, are discussed.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300080405
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“Sedimentation rate of the floodplain sediments of the Yamuna river basin (tributary of the river Ganges, India) by using <tex>210Pb</tex>, and <tex>137Cs</tex>, techniques”. Saxena DP, Joos P, Van Grieken R, Subramanian V, Journal of radioanalytical and nuclear chemistry 251, 399 (2002). http://doi.org/10.1023/A:1014821906600
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1023/A:1014821906600
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“Laminated altered layers in historical glass : density variations of silica nanoparticle random packings as explanation for the observed lamellae”. Schalm O, Anaf W, Journal of non-crystalline solids 442, 1 (2016). http://doi.org/10.1016/J.JNONCRYSOL.2016.03.019
Abstract: One of the most striking but unexplained phenomena in the natural degradation of glass is the transformation of an almost colorless, transparent and homogeneous glass into a colored, opaque and heterogeneous degradation layer. In many cases, the degradation layer consists of numerous lamellae with a thickness between 0.1 and 10 pm. However, both internal structure and formation proess of laminated degradation layers remain unclear. In this paper, a model is proposed where we assume that transformed (degraded) glass consists of a random packing of nano-sized silica particles while the lamellae are the result of different packing densities. The model is able to connect the texture of numerous lamellae observed by several types of microscopic techniques with the structure at molecular level determined by means of chemical analysis. In addition, the model is able to explain numerous properties such as the parameters responsible for the contrast between lamellae. This contrast can be caused by differences in color, density, elemental composition, or surface roughness. (C) 2016 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1016/J.JNONCRYSOL.2016.03.019
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“New generation monitoring devices for heritage guardians to detect multiple events and hazards”. Schalm O, Anaf W, Callier J, Leyva Pernia D, IOP conference series : materials science and engineering 364, Unsp 012056 (2018). http://doi.org/10.1088/1757-899X/364/1/012056
Abstract: Environmental parameters such as temperature, relative humidity, visible light, UV radiation and pollution influence the deterioration rate of heritage items. To judge on the environmental appropriateness for heritage conservation, it is therefore important to monitor the environment. Often, an incomplete set of environmental parameters is measured, or sporadic or time-averaged measurements are performed. As a result, a wide range of undesirable situations and hazards remain unnoticed. This might lead to an underestimation of environmental dangers (i.e., inaccurate judgement) or to inappropriate mitigation measures (i.e., inaccurate decision making). We present an innovative and user-friendly monitoring device that simultaneously and continuously measures (1) environmental parameters and (2) material behavior. An extended combination of off-the-shelf sensors for temperature, relative humidity, air speed, CO2, NO2, O-3 and particulate matter are connected to a multipurpose datalogger. In-house developed sensors for the shrinkage and expansion behavior of wood, as well as sensors for metal corrosion rates are connected to the same datalogger. Such extended monitoring shows the identification of a wider range of undesirable situations, and it facilitates the search for correlations between such situations and the sources that cause them, i.e., the hazards.
Keywords: P1 Proceeding; Engineering sciences. Technology; Art; History; Antwerp Systems and software Modelling (AnSyMo); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1088/1757-899X/364/1/012056
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“A decision support system for preventive conservation : from measurements towards decision making”. Schalm O, Cabal A, Anaf W, Leyva Pernia D, Callier J, Ortega N, The European Physical Journal Plus 134, 74 (2019). http://doi.org/10.1140/EPJP/I2019-12441-5
Abstract: We present a decision-support system that guides heritage guardians in selecting mitigation actions to improve the indoor air quality and thus the preservation conditions of indoor collections in heritage buildings. This contribution shows that it is feasible to build a decision support system dedicated to preventive conservation when the following barriers are overcome: 1) simultaneous measurement of a wide range of environmental parameters in order to detect a larger number of undesired situations; 2) development of an algorithm to perform reproducible indoor air quality assessments; and 3) transformation of the air quality assessment into a graph that can be read intuitively without causing a wide variation of interpretations among stakeholders. An important aspect of the decision support system is that it reduces several sources of uncertainty that hamper reliable indoor air quality assessments. The possibilities of such a system are illustrated with a measurement campaign in a church where a heating system has been installed and used for the first time.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Systems and software Modelling (AnSyMo); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1140/EPJP/I2019-12441-5
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“Improved radiographic methods for the investigation of paintings using laboratory and synchrotron X-ray sources”. Schalm O, Cabal A, van Espen P, Laquière N, Storme P, Journal of analytical atomic spectrometry 26, 1068 (2011). http://doi.org/10.1039/C0JA00242A
Abstract: It is generally known that radiographic inspection of 1517th century paintings can easily be done with a polychromatic X-ray source using a voltage between 20 kV and 40 kV in combination with classic X-ray films. Unfortunately, the spatial structure of numerous 19th and early 20th century paintings cannot be visualized with conventional radiography due to several reasons such as the use of lead white grounds or low absorbing pigments. Radiographic images are blurred or worse, they do not contain the picture of the painting. During the last decades, many technological innovations have been introduced in the field of radiography but their possibilities in cultural heritage have not been explored in full detail. In our investigation we used phosphor imaging plates, energy dispersive detectors and CCD-cameras in combination with synchrotron radiation and conventional X-ray tubes in order to improve the quality of radiographic images. Several promising techniques that could improve the quality of radiographs of paintings were identified.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1039/C0JA00242A
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Schalm O, Caen J, Janssens K (2007) Chemical composition of 19th century window glass originating from stianed glass windows located in Belgium. 169–178
Keywords: P2 Proceeding; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Homogeneity, composition and deterioration of window glass fragments and paint layers from two seventeenth-century stained glass windows created by Jan de Caumont (similar to 1580-1659)”. Schalm O, Caen J, Janssens K, Studies in conservation 55, 216 (2010). http://doi.org/10.1179/SIC.2010.55.3.216
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 0.578
Times cited: 2
DOI: 10.1179/SIC.2010.55.3.216
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“Chemical composition and deterioration of glass excavated in the 15th-16th century fishermen town of Raversijde (Belgium)”. Schalm O, Caluwé, D, Wouters H, Janssens K, Verhaeghe F, Pieters M, Spectrochimica acta: part A: molecular and biomolecular spectroscopy 59, 1647 (2004). http://doi.org/10.1016/J.SAB.2004.07.012
Abstract: The chemical composition, as determined by electron probe X-ray microanalysis of a series of ca. 100 archaeological glass fragments, excavated at the Raversijde site (Belgium) is discussed. In the 15th-16th century, Raversijde was a flourishing fishermen town located on the shore of the North Sea, close to the city of Ostend. As a consequence of several battles that were fought in its vicinity, the site was abandoned in the 16th century and was not occupied since then. It is one of the rare archaeological sites in Europe that contains a significant amount of information on the daily life inside a small but affluent medieval community. A comparison of the chemical composition of fragments of vessels and window glass encountered in Raversijde to those found in urban centres in Belgium and to literature date on German and French archaeological finds shows that glass made with wood ash dominates. Usually, it concerns artifacts with a predominantly utilitarian use. A few objects made with sodic (i.e., Na-rich) glass were also encountered, likely to have been imported from Venice during the 15th century or in later periods from an urban centre such as Antwerp, where Facon-de-Venice glass manufacturing activities were established near the start of the 16th century. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.536
Times cited: 26
DOI: 10.1016/J.SAB.2004.07.012
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“A methodology for the identification of glass panes of different origin in a single stained glass window: application on two 13th century windows”. Schalm O, de Raedt I, Caen J, Janssens K, Journal of cultural heritage 11, 487 (2010). http://doi.org/10.1016/J.CULHER.2010.05.004
Abstract: The chemical composition of 11 glass panes originating from two 13th century non-figurative windows were analyzed by means of Scanning Electron MicroscopyEnergy Dispersive X-ray system (SEM-EDX). The windows were discovered in the back-wall of the triforium during the restoration of the choir of the cathedral St. Michael and St. Gudule in Brussels (Belgium). In order to determine if these windows were fabricated with glass of different origin or not, the compositional difference between the panes were compared with the variation in composition as a result of the following causes: (1) compositional fluctuation between panes cut from the same sheet of glass, (2) compositional fluctuation caused when panes are cut from different sheets that were made with the same batch, (3) compositional fluctuation caused when the glass is made from different batches at the same production center, and (4) compositional fluctuation as a result of glass produced at different fabrication centers.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.838
Times cited: 7
DOI: 10.1016/J.CULHER.2010.05.004
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“A flexible and accurate quantification algorithm for EPXMA based on thin-film element yields”. Schalm O, Janssens K, Spectrochimica acta: part B : atomic spectroscopy 58, 669 (2003). http://doi.org/10.1016/S0584-8547(02)00290-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.241
DOI: 10.1016/S0584-8547(02)00290-2
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“Characterization of the main causes of deterioration of grisaille paint layers in 19th C. stained-glass windows by J.-B. Capronnier”. Schalm O, Janssens K, Caen J, Spectrochimica acta: part B : atomic spectroscopy 58, 589 (2003). http://doi.org/10.1016/S0584-8547(02)00282-3
Abstract: Twenty-seven glass fragments containing dark coloured grisaille paint layers of different qualities were collected from ten windows of the cathedral St. Michael & St. Gudule in Brussels (Belgium). The windows were made by J.-B. Capronnier (18141891) and cover the period between 1843 and 1878. The samples were cross-sectioned and examined in an electron microscope. Grisaille paint layers are not homogeneous and therefore, it is not meaningful to characterize them in terms of their average composition. Instead, parameters such as granularity, the number of residual gas bubbles per running millimetre of paint, the type of pigments, and the thickness of the paint layer were used to characterize them. The microscopic morphology allows a classification of the grisaille paint layers in four groups, every group associated with a quality level. Moreover, the main causes of the accelerated degradation of some of these paint layers could be explained. The classification made it possible to distinguish two periods in the work of Capronnier: (1) the early period (18431848) is characterized by the presence of either single granular paint layers or of double-layered systems consisting of a granular paint layer on top of a well-melted paint layer. The granular grisaille paint layers tend to pulverize; (2) the later period (18481878) is characterized by the presence of only well-vitrified paint layers. No sign of deterioration was found on the well-vitrified paint layers.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.241
DOI: 10.1016/S0584-8547(02)00282-3
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“Chemische en morfologische karakterisatie van de grissailles van Capronnier met behulp van EPXMA”. Schalm O, Janssens K, Caen J, Adams F, (1999)
Keywords: P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Composition of 12-18th century window glass in Belgium : non-figurative windows in secular buildings and stained-glass windows in religious buildings”. Schalm O, Janssens K, Wouters H, Caluwé, D, Spectrochimica acta: part B : atomic spectroscopy
T2 –, 18th International Congress on X-Ray Optics and Microanalysis, September 25-30, 2005, National Institute of Nuclear Physics, Frascati, Italy 62, 663 (2007). http://doi.org/10.1016/J.SAB.2007.03.006
Abstract: A set of ca. 500 window glass fragments originating from different historical sites in Belgium and covering the period 12(th)- 18(th) century was analyzed by rneans of electron probe microanalysis. Most samples are archaeological finds deriving from non-figurative windows in secular buildings. However. the analyzed set also contains glass sampled from still existing non-figurative windows in secular buildings and stained-glass windows in religious buildings. A sudden compositional change at the end of the 14(th) century can be noticed among the series of glass compositions that were obtained. These changes could be related to the use of different glassmaker recipes and to the introduction of new raw materials for glass making. (c) 2007 Elsevier B.V All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.241
Times cited: 50
DOI: 10.1016/J.SAB.2007.03.006
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“Some critical observations about the degradation of glass : the formation of lamellae explained”. Schalm O, Nuyts G, Janssens K, Journal Of Non-Crystalline Solids 569, 120984 (2021). http://doi.org/10.1016/J.JNONCRYSOL.2021.120984
Abstract: This study demonstrates that the mechanism responsible for the transformation of glass into a degradation layer is pH-dependent. In acid conditions, the transformed glass is homogeneous and brittle. In mild alkaline conditions, transformed glass is heterogeneous due to the presence of lamellae composed of silica nanoparticles and the occurrence of Ca-rich inclusions. The fundamental difference between acid and alkaline conditions cannot be explained by the currently accepted degradation mechanism based on ion exchange. To explain this critical observation, we propose a refined degradation mechanism based on existing knowledge that involves several inwardly moving reaction fronts. The fronts responsible for the transformation of the silicate network into amorphous silica are also responsible for the morphology of the transformed glass. We have identified the feedback mechanism that explains the formation of lamellae in alkaline conditions.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.124
DOI: 10.1016/J.JNONCRYSOL.2021.120984
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“Manganese staining of archaeological glass : the characterization of Mn-rich inclusions in leached layers and a hypothesis of its formation”. Schalm O, Proost K, De Vis K, Cagno S, Janssens K, Mees F, Jacobs P, Caen J, Archaeometry 53, 103 (2011). http://doi.org/10.1111/J.1475-4754.2010.00534.X
Abstract: During the study of a large number of archaeological glass fragments, manganese-rich inclusions in leached layers were observed in a limited number of cases. This phenomenon occurs only in black-coloured leached layers. Since the formation mechanism of such manganese-rich inclusions is still unclear, a combination of several analytical techniques was used in order to investigate this phenomenon and, more specifically, to obtain more information on (a) the composition and morphology of the inclusions, (b) the chemical state of Mn and (c) the 3D morphology of the inclusions. A mechanism that might explain the formation of these inclusions is proposed.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.47
Times cited: 24
DOI: 10.1111/J.1475-4754.2010.00534.X
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“Enamels in stained glass windows: preparation, chemical composition, microstructure and causes of deterioration”. Schalm O, van der Linden V, Frederickx P, Luyten S, van der Snickt G, Caen J, Schryvers D, Janssens K, Cornelis E, van Dyck D, Schreiner M, Spectrochimica acta: part B : atomic spectroscopy 64, 812 (2009). http://doi.org/10.1016/j.sab.2009.06.005
Abstract: Stained glass windows incorporating dark blue and purple enamel paint layers are in some cases subject to severe degradation while others from the same period survived the ravages of time. A series of dark blue, greenblue and purple enamel glass paints from the same region (Northwestern Europe) and from the same period (16early 20th centuries) has been studied by means of a combination of microscopic X-ray fluorescence analysis, electron probe micro analysis and transmission electron microscopy with the aim of better understanding the causes of the degradation. The chemical composition of the enamels diverges from the average chemical composition of window glass. Some of the compositions appear to be unstable, for example those with a high concentration of K2O and a low content of CaO and PbO. In other cases, the deterioration of the paint layers was caused by the less than optimal vitrification of the enamel during the firing process. Recipes and chemical compositions indicate that glassmakers of the 1617th century had full control over the color of the enamel glass paints they made. They mainly used three types of coloring agents, based on Co (dark blue), Mn (purple) and Cu (light-blue or greenblue) as coloring elements. Bluepurple enamel paints were obtained by mixing two different coloring agents. The coloring agent for redpurple enamel, introduced during the 19th century, was colloidal gold embedded in grains of lead glass.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Vision lab
Impact Factor: 3.241
Times cited: 28
DOI: 10.1016/j.sab.2009.06.005
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“Composition of 13-17th century glass from non-figurative windows in secular buildings excavated in Belgium”. Schalm O, Wouters H, Janssens K, (2005)
Keywords: P3 Proceeding; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“The use of a secondary cathode to analyse solid non-conducting samples with direct current glow discharge mass spectrometry: potential and restrictions”. Schelles W, de Gendt S, Maes K, Van Grieken R, Fresenius' journal of analytical chemistry 355, 858 (1996). http://doi.org/10.1007/S0021663550858
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/S0021663550858
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“Evaluation of secondary cathodes for glow discharge mass spectrometry analysis of different nonconducting sample types”. Schelles W, de Gendt S, Müller V, Van Grieken R, Applied spectroscopy 49, 939 (1995). http://doi.org/10.1366/0003702953964741
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1366/0003702953964741
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“Optimization of secondary cathode thickness for direct current glow discharge mass spectrometric analysis of glass”. Schelles W, de Gendt S, Van Grieken RE, Journal of analytical atomic spectrometry 11, 937 (1996). http://doi.org/10.1039/JA9961100937
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1039/JA9961100937
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“Direct current glow discharge mass spectrometric analysis of Macor ceramic using a secondary cathode”. Schelles W, Van Grieken R, Analytical chemistry 68, 3570 (1996). http://doi.org/10.1021/AC960441U
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC960441U
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“Direct current glow discharge mass spectrometry for elemental characterization of polymers”. Schelles W, Van Grieken R, Analytical chemistry 69, 2931 (1997). http://doi.org/10.1021/AC970186T
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC970186T
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“Quantitative analysis of zirconium oxide by direct glow discharge mass spectrometry using a secondary cathode”. Schelles W, Van Grieken R, Journal of analytical atomic spectrometry 12, 49 (1997)
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Respiratory muscle activity after spontaneous, neostigmine- or sugammadex-enhanced recovery of neuromuscular blockade : a double blind prospective randomized controlled trial”. Schepens T, Janssens K, Maes S, Wildemeersch D, Vellinga J, Jorens PG, Saldien V, BMC anesthesiology 19, 187 (2019). http://doi.org/10.1186/S12871-019-0863-Y
Abstract: Background The use of neostigmine after neuromuscular blockade (NMB) has been associated with postoperative respiratory complications. In previous studies, we found lower diaphragmatic activity after neostigmine reversal of NMB, compared to sugammadex. It is still unclear whether the adequate use of neostigmine guarantees normal respiratory muscle function after NMB. In this study, we wanted to assess the effect of commonly used degrees of NMB and their possible reversal strategies on respiratory muscle activity after the return of normal neuromuscular transmission. Methods This is a randomized, controlled, parallel-group, single-centre, double-blind study in patients scheduled for intracranial surgery at a tertiary academic hospital in Belgium. All participants received target controlled propofol/remifentanil anesthesia and were randomized into one of five groups, receiving either a shallow NMB with no reversal (shallow/saline), a shallow NMB with sugammadex reversal (shallow/sugammadex), a moderate NMB with neostigmine reversal (moderate/neostigmine), a moderate NMB with sugammadex reversal (moderate/sugammadex), or a deep NMB with sugammadex reversal (deep/sugammadex). Primary and secondary outcome parameters were diaphragm and intercostal electromyographic (EMG) activity at the moment of resumed spontaneous breathing activity, defined as a maximal interval of 10 min after the first spontaneous breath. Results For the five groups, a total of 55 patients could be included in the final analysis. Median time of spontaneous breathing analyzed was 5 min (IQR 3-9.5 min). Both the moderate/sugammadex and the moderate/neostigmine groups had lower levels of diaphragm EMG compared to the shallow/sugammadex group. The moderate/neostigmine group had lower levels of intercostal EMG activity compared to the shallow/saline group. Conclusions In this study, the depth of neuromuscular blockade and type of reversal strategy impacts respiratory muscle activity at the moment of resumed spontaneous breathing and recovery of neuromuscular blockade. Both groups that received moderate NMB had lower levels of diaphragm EMG, compared to the shallow NMB group with sugammadex reversal. Compared to the shallow NMB group with no reversal, the moderate NMB with neostigmine reversal group had lower intercostal EMG activity.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Surgical Training, Anatomy and Research Centre (ASTARC); Laboratory Experimental Medicine and Pediatrics (LEMP)
Impact Factor: 1.525
DOI: 10.1186/S12871-019-0863-Y
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“Determination of light elements in marine aerosols by grazing-emission X-ray fluorescence”. Schmeling M, Van Grieken R, (1999)
Keywords: P3 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Sample preparation for X-ray fluorescence”. Schmeling M, Van Grieken RE page 933 (2002).
Keywords: H3 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Micro-XANES determination of ferric iron and its application in thermobarometry”. Schmid R, Wilke M, Ober R, Dong S, Janssens K, Falkenberg G, Franz L, Gaab A, Lithos 70, 381 (2003). http://doi.org/10.1016/S0024-4937(03)00107-5
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0024-4937(03)00107-5
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“Identifying Electrochemical Fingerprints of Ketamine with Voltammetry and Liquid Chromatography–Mass Spectrometry for Its Detection in Seized Samples”. Schram J, Parrilla M, Sleegers N, Samyn N, Bijvoets SM, Heerschop MWJ, van Nuijs ALN, De Wael K, Analytical Chemistry 92, 13485 (2020). http://doi.org/10.1021/acs.analchem.0c02810
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.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 7.4
DOI: 10.1021/acs.analchem.0c02810
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“Electrochemical profiling and liquid chromatography–mass spectrometry characterization of synthetic cathinones : from methodology to detection in forensic samples”. Schram J, Parrilla M, Sleegers N, Van Durme F, van den Berg J, van Nuijs ALN, De Wael K, Drug Testing And Analysis 13, 1282 (2021). http://doi.org/10.1002/DTA.3018
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.
Keywords: A1 Journal article; Pharmacology. Therapy; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 3.469
DOI: 10.1002/DTA.3018
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