Novel methods for the detection of historical biocidal residues in heritage environments

  • Iain David Rushworth

Student thesis: Doctoral Thesis


Work in this thesis is comprised of three inter-related projects to develop methods for detection of biocide residues in heritage environments. In the first phase of the work gas- or liquid-chromatographic methods of analyses were developed to detect 10 target analytes (aldrin, camphor, chloronaphthalene, dichlorodiphenyltrichloroethane, dichlorvos, dieldrin, endrin, hexachlorocyclohexane, naphthalene and thymol). The results obtained were summarised in a flowchart that could be easily interpreted by potential end-users (non-scientific personnel in heritage environments). The utility of the methods was demonstrated by performing a number of case studies in U.K. based heritage institutions. A number of the target analytes (camphor, chloronaphthalene, hexachlorocyclohexane, naphthalene) were successfully detected in the vapour-phase across several institutions and a tentative identification of dichlorvos was made after swabbing a case study object. The sampling technique for the developed methods was performed by museum staff after sending samplers to institutions via Royal Mail, highlighting the ease with which sample collection for these techniques can be conducted. The analysis showed that the concentrations of the substances detected in air were not likely to pose a significant hazard to human health, demonstrating the potential of the developed methods for use as a means of determining the safety of those working with the contaminated objects. In the second phase of work, an agar sensor was loaded with an immobilised enzyme, acetylcholinesterase, to develop a sensor for the detection of organophosphates in swab or vapour-phase samples. The presence of a model organophosphate (dichlorvos) inhibited a colour change reaction in which the enzyme substrate, indoxyl acetate, was oxidised to indigo after undergoing an enzyme-catalysed hydrolysis.This sensor potentially has significant advantages over current methods of detection for organophosphate pesticides in heritage institutions, as it was shown to be simple, cheap, easy to use and did not require specialist training or equipment to perform the analysis or determine the result. The developed method had a detection limit of 13 mg dm-3 dichlorvos in solution, and masses of as low as 20 μg were shown to provide positive results when collected using a swab. Furthermore, the gels developed have a shelf life of several weeks and are thus easily transported for use within heritage institutions. Significantly, the developed organophosphate sensor was also demonstrated to work in the vapour-phase, possibly allowing objects considered too fragile for contact sampling to be tested for the presence of organophosphate pesticides. Finally, preliminary work was conducted to develop a method for the determination of mercury in heritage environments. Silica xerogel or agar hydrogel supports were used to immobilise diphenylcarbazone (DPC), a colorimetric reagent used for the detection of mercury, in order to address an unmet need for simple and cost-effective detection of organic biocides. Agar gel was considered to be the most suitable matrix and was used to form the basis of a cheap, easy to use, selective and sensitive method for the detection of mercury chloride in heritage environments.This work was concluded by spiking simulated objects with mercury chloride solution, following detection with the newly developed sensor. The sensor was shown to produce a colour change that was readily observable using the naked eye down to concentrations of 10 mg dm-3 without the need for instrumentation, offering a significant cost advantage over established techniques for the detection of mercury in heritage institutions such as x-ray fluorescence spectrometry. DPC gels were also shown to be effective when dried. This significantly extended the shelf life of the DPC reagent, which, according to literature
Date of Award15 Dec 2016
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsAHRC (Arts and Humanities Research Council)
SupervisorLorraine Gibson (Supervisor) & Christine Davidson (Supervisor)

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