Sarah L. Cresswell

Recent Advances in the Application of Stable Isotope Ratio Analysis in Forensic Chemistry

This review paper updates the previous literature in relation to the continued and developing use of stable isotope ratio analysis in samples which are relevant to forensic science. Recent advances in the analysis of drug samples, explosive materials, and samples derived from human and animal samples are discussed. The paper also aims to put the use of isotope ratio mass spectrometry into a forensic context and discuss its evidential potential.

Evaluation of on-line methodology for microwave-assisted extraction of polycyclic aromatic hydrocarbons (PAHs) from sediment samples

The development of novel on-line microwave techniques is described for the selective extraction of polycyclic aromatic hydrocarbons from sediment samples. Two flow systems were evaluated, in the first, samples of sediment were slurried in water and on passing through the microwave the analytes were extracted and subsequently trapped onto a C18 cartridge. Elution from the in-line C18 cartridge directly onto an analytical HPLC column was then performed. In the second study, samples were slurried in acetone and passed through the microwave cavity. The effluent was then shaken with 10 ml of hexane in order to pre-concentrate the extracted components, which were detected and quantified by GC-MS. Recoveries from the second technique on average ranged from 62 to 93% (0.28–8.15 µg). Both techniques were compared to the standard EPA method for microwave-assisted solvent extraction. The second method based on acetone, was found to give comparable recoveries to the EPA method, but offered significant improvement in the precision for replicate samples which were found to be in the range 2–7% RSD compared to 6–16% RSD for the batch technique.

Amine-rich carbon nanodots as a fluorescence probe for methamphetamine precursors

Amine-functionalized carbon dots (A-CDs) were synthesized by one-step hydrothermal reaction of urea and citric acid. The purified CD sample exhibits a surface states dominated fluorescence emission with a quantum yield of 30%. The A-CDs demonstrate excellent sensitivity toward methamphetamine pre-precursor and precursor, and a remarkable selectivity against common drug cutting agents (diluents) such as aspirin, paracetamol, etc. The specific selectivity of CDs towards such type of drug precursor molecules is first time reported, which appears to be related to the spatial distribution of the surface functional groups. The fluorescence-based sensing mechanism is revealed by a detailed analysis on the static and dynamic fluorescence behaviour. We further demonstrated an immobilization strategy for fabricating solid-state sensors, and the retained sensitivity of the A-CDs after immobilization. The study reveals the potential of the use of a CDs as an effective sensing probe for illicit drugs, which is in demand.

Isotopic profiling of seized benzylpiperazine and trifluoromethylphenylpiperazine tablets using δ13C and δ15N stable isotopes

This paper demonstrates the use of isotopic analysis of 23 benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) containing tablets seized on two independent occasions by the Northern Territory (NT) Police, Australia. Isolation (High Performance Liquid Chromatography (HPLC)) of BZP and TFMPP followed by Isotope Ratio Mass Spectrometry (IRMS) (carbon and nitrogen stable isotopes) analysis was performed. Results are presented for δ13C and δ15N values of the respective piperazine analogues. The isotopic data and statistical analysis suggest a common source of manufacture for the BZP samples but suggest different sources for the TFMPP isolated from the corresponding BZP containing tablets investigated. The use of IRMS in this case study demonstrated the ability to obtain information regarding the BZP/TFMPP sources unattainable via conventional chemical analysis.

Rapid synthesis of magnesium aluminophosphate-5 by microwave dielectric heating

A new microwave-hydrothermal technique has been used to synthesise magnesium aluminophosphate-5, which is formed in 20 min at pressures from 130 to 175 psi and has a significantly increased surface area compared to conventionally prepared samples; below 130 psi incomplete crystallisation occurred.

Investigation of the l-phenylacetylcarbinol process to substituted benzaldehydes of interest

The large scale industrial manufacture of the nasal decongestant pseudoephedrine is typically carried out by the reductive amination of l-phenylacetylcarbinol (l-PAC), which in turn is produced via the biotransformation of benzaldehyde using yeast. In recent years there has been increasing legislative control of the supply of pseudoephedrine due to it being diverted for the clandestine production of methylamphetamine and there is some evidence that a number of clandestine drug laboratory chemists have considered the application of the l-PAC process to manufacture their own pseudoephedrine. This work examined the use of a number of substituted benzaldehydes for the manufacture of the corresponding substituted l-PAC analogue followed by reductive amination to the corresponding substituted pseudoephedrine/ephedrine analogues. These substituted pseudoephedrine/ephedrine analogues were either reduced or oxidised to determine the feasibility of producing the corresponding methylamphetamine or methcathinone analogues. As a result, the l-PAC process was identified as a viable route for synthesis of substituted methylamphetamines and methcathinones.

Chapter 17 Extraction techniques for solid samples

Publisher Summary Extraction is normally a laboratory procedure prior to analysis. The choice of extraction technique is often made based on what is available and what has been used before. The skill and experience of the analyst is often the key to the operation of extraction and analysis procedures. Extraction of organic pollutants from solid environmental samples has frequently been done using organic solvents with or without the addition of heat. This process is typified by the technique of Soxhlet extraction. A flow diagram detailing a procedure for the extraction of analytes from soils using Soxhlet extraction is shown. Soxhlet extraction normally requires large volumes of chlorinated solvent to be refluxed through the solid sample for an extended period. Although it is not uncommon for the analyst to assemble several experimental set-ups at the same time, it can be labor-intensive at the start and end of the process. As the process is time-consuming, alternative extraction strategies have been developed based on instrumentation that allows the process to be controlled more effectively. This chapter mainly focuses on these newer instrumental approaches to compare and contrast both their application base and robustness for extraction.

Development of techniques for determination of primary components of dental medicament paste mixtures for root canal treatment

AIMS The purpose of the present study was to develop techniques to evaluate and quantify the primary components of dental medicament paste mixtures for root canal treatment, and to evaluate if degradation of the primary components occurred during storage. METHODS The first part of the study developed a mass spectrometry (MS) method for determination of best recovery process. For this process, analytical grades of triamcinolone acetonide, clindamycin HCl, and doxycycline hyclate were sourced and analyzed. This was followed by solid-phase extraction (SPE) and an analysis of active components in dental pastes. RESULTS By utilizing the targeted analytical properties of multiple reaction monitoring MS methods, coupled with SPE technique, the active components of endodontic dental pastes could be quantified and compared. The developed methods showed consistency over multiple runs, with a high level of reproducibility. None of the active components of the tested pastes degraded over the periods of product life tested. CONCLUSION The inactivation or destruction of any of the primary components of endodontic medicaments in storage, or when mixed with other pastes, could affect treatment outcomes. The present study provides a reliable technique for the analysis of the active components of root canal medicaments.

The Reluctance of Scientists to Engage in Peer Review of Teaching

Over the last two decades universities globally have responded to a growing demand for higher education and hence the number and diversity of university students has increased dramatically (Bradley, Noonan, Nugent, & Scales, 2008; Universities Australia, 2013). At the same time publicly funded universities have faced decreasing budgets leading to radical changes in the delivery of education.