Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Improved forensic hair evidence for drugs of abuse by mass spectrometry
    Duvivier, W.F. - \ 2016
    Wageningen University. Promotor(en): Michel Nielen, co-promotor(en): Teris van Beek. - Wageningen : Wageningen University - ISBN 9789462578159 - 194
    forensic science - hair - analytical methods - spectrometry - forensische wetenschap - haar - analytische methoden - spectrometrie

    Forensic hair analysis can be used as alternative evidence next to body fluids, and to obtain retrospective timeline information of an individual’s drug exposure. Chapter 1 describes the general concepts of drug incorporation into hair, external contamination, and the current status and limitations of hair analysis methods are introduced. Furthermore, an overview of ambient ionization techniques is given, with emphasis on direct analysis in real time (DART).
    The instrumentation, ionization mechanisms, and application range of DART are presented. Scientific challenges and objectives to improve forensic hair evidence are formulated, which formed the basis of the research presented in this thesis.

    A major issue in forensic hair analysis is the possibility of false-positive results due to external contamination. In Chapter 2, an evidence-based evaluation of decontamination protocols for the removal of cannabinoid contamination is presented, mainly focused on
    Δ9-tetrahydrocannabinol (THC). Different solvents were extensively tested for their ability to remove cannabinoid contamination originating from cannabis smoke or indirect contact with cannabis plant material. After selection of the most efficient solvents, different sequential wash steps were tested on externally contaminated blank hair samples. Finally, application of the three best performing protocols on cannabis users’ hair, both as such and after deliberate contamination, resulted in removal of all contamination without removing incorporated THC. From the detailed scientific evidence reported in this chapter, a protocol using a single methanol wash followed by a single aqueous SDS solution is recommended to remove external cannabis contamination.

    A novel approach for the analysis of intact locks of hair consisting of DART combined with high resolution mass spectrometry (HRMS) is developed in Chapter 3. DART–HRMS settings were optimized for the analysis of THC and the accuracy of the probed hair zone was investigated using spiked blank hair samples. Intact locks of hair could be longitudinally scanned without the need of extensive sample preparation, resulting in analysis times of only minutes. Detection of THC was achieved in several hair samples from cannabis users. A quantitative liquid chromatography (LC)–MS/MS method was developed, in-house validated, and used to confirm the presence of THC in drug user hair samples. With a retrospective timeline accuracy of ±2 weeks, a significant improvement over conventional segmented hair analysis was achieved. Moreover, differentiation between zones of different THC content within a DART hair scan could be made, indicating possibilities for retrospective assessment of time of drug use.

    The DART hair scan method has been improved and expanded in Chapter 4. Targeted detection of four commonly used drugs of abuse (amphetamine, cocaine, MDMA and THC) with structural confirmation was achieved by data-dependent product ion scans. Simultaneously,
    full-scan high-resolution data was obtained and retrospectively interrogated versus a list of more than a hundred, less common, drugs of abuse and occasionally abused pharmaceutical drugs. The hair scan method was validated for the analysis of cocaine against an accredited LC–MS/MS method and the detection limit for cocaine was found to comply with the cut-off value of 0.5 ng/mg. Hair samples of 10 different drug users were analyzed. Next to detection of the four targeted drugs of abuse, retrospective data interrogation revealed several additional hits. The detected substances correlated well with reported drug use and by the detection of several metabolites, drug use could be unambiguously proven. The retrospective timeline accuracy was further improved by use of a high spatial resolution DART exit cone, which yielded a DART spot size corresponding to approximately 10 days of hair growth.

    When direct and/or ambient ionization techniques are used to analyze intact hair samples, endogenous isobaric ions can overlap with compounds of interest and yield
    false-positive results. The selectivity of four MS instruments with different mass analyzers (orbitrap, quadrupole orbitrap, triple quadrupole, time-of-flight) was evaluated in Chapter 5 by DART analysis of THC from hair samples. To avoid overlap of THC with isobaric ions originating from the hair matrix, a mass resolution of at least 30,000 FWHM was necessary. The use of travelling wave ion mobility spectrometry (TWIMS) resulted in increased selectivity by separation of isobaric ions based on their drift times. A triple quadrupole instrument in multiple reaction monitoring (MRM) mode was found to have the best sensitivity, however, the used transitions were not specific enough for use on drug user hair samples. Thus the selectivity needed to indisputably differentiate THC from endogenous isobaric ions in drug user hair samples could only be achieved by the high resolution of the tested orbitrap MS instruments.

    Chapter 6 demonstrates the application of forensic hair analysis techniques to veterinary control. Timeline information could be obtained from veterinary hair samples. For this purpose, a UPLC–MS/MS hair analysis method was adapted and optimized for smaller sample sizes.
    After validation of the method, segmented hair samples obtained from clenbuterol-treated calves using the forensic hair sampling protocol were analyzed and clenbuterol concentration profiles along the hair samples could be obtained. Assessment of the average growth rate of calf tail hair enabled retrospective determination of time of clenbuterol administration.
    The estimated time of administration was reproducible when analyzing sub-samples taken from the same lock of hair and duplicate locks of hair, and in good correlation with the actual treatment.

    Through the research presented in this thesis, novel approaches in hair analysis have been developed and the value of forensic hair evidence improved considerably. In Chapter 7, the main achievements of this thesis are discussed in detail and an insight in the future perspectives of hair analysis and ambient ionization is given. Potential further applications of the DART hair scan method, and ambient ionization in general, are presented, including some preliminary results of new decontamination strategies, hair analysis possibilities, and other forensic uses of DART ionization.

    Sensing food fraud from analytical chemistry and criminological perspectives
    Ruth, S.M. van; Huisman, W. ; Luning, P.A. - \ 2013
    voedselveiligheid - authenticiteit - herkomst - analytische scheikunde - forensische wetenschap - food safety - authenticity - provenance - analytical chemistry - forensic science
    The joint investigation of analytical opportunities for authentication and understanding the influece of peoples’ motives and agri-food chain context characteristics on fraud, will provide input for a new approach towards fraud risks assessment for food industries and regulators.
    A statistical model for inspection procedures in forensic and environmental analysis
    Ruig, W.G. de; Jansen, A.A.M. ; Huf, F.A. - \ 1991
    Wageningen : DLO-State lnstitute for Quality Control of Agricultural Products (Report / RIKILT-DLO 91.62) - 23
    statistische analyse - voedselkwaliteit - kwaliteitscontroles - milieu - verontreiniging - monitoring - forensische wetenschap - statistical analysis - food quality - quality controls - environment - pollution - monitoring - forensic science
    Legal regulations on composition and safety of food products require inspeetion programs to maintain the decisions or to get insight in the real situation. Such programs consist of a sampling procedure followed by analysis of the samples. In monitoring of environmental contamination similar programs are required. When large quantities of samples for monitoring of contaminants in environment or in food chains have to be analysed, and the majority of the samples fulfills the legal requirements, a two stage control system will be attractive. In the first stage samples are analysed by a simple 'screening method', to sift out the large number of samples fulfilling the requirements ('negative result'). The minor part of samples not fulfilling the requirernents ('positive result') are further investigated by a sophisticated 'confirrnatory method', specific tor the analyte(s) of interest, for an uitimate judgement. For this kind of inspeetion a simple model is used in this study, in order to calculate the fraction of false negative results in the inspection.
    De deelneming van deskundigen aan rechtspraak : toegespitst op agrarische zaken
    Visser, P. de - \ 1971
    Wageningen University. Promotor(en): J.M. Polak. - Deventer : Kluwer - ISBN 9789026805097 - 130
    recht - forensische wetenschap - gerechtelijke geneeskunde - wetgeving - bewoning - pachtovereenkomsten - huur - landbouw - nederland - rechterlijke organisatie - rechtsgang - law - forensic science - forensic medicine - legislation - tenancy - leases - rent - agriculture - netherlands - judicial organization - legal procedure
    De indeling van dit proefschrift is als volgt:

    I. In het eerste deel zal een beschrijving gegeven worden van de vormen van rechtspraak die geschiedt door of met medewerking van vakdeskundigen. Hierbij zal zoveel mogelijk de historische ontwikkeling in het oog worden gehouden. Tevens zal ik proberen na te gaan waarom en hoe deze afwijkingen van de rechtspraak door de gewone rechter zijn ontstaan.

    II. In deel II zullen de in het eerste deel gevonden motieven tot afwijking van de gewone rechtspraak worden geëvalueerd. Wat zal er c.q. moet er verder gebeuren?

    Hoe zal de toekomstige ontwikkeling van de rechtspraak zijn? Zal het deelnemen van specifieke deskundigen aan de rechtspraak toe- of afnemen? Op deze en andere vragen zal ik in dit deel trachten een antwoord te vinden. Hierbij zal ik o.a. gebruik maken van de antwoorden op twee door mij verstuurde vragenlijsten.

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