Will Meredith

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Gas chromatography/mass spectrometry (GC/MS) is the preferred technique for the detection of urinary steroid androgens for drug testing in athletics. Excreted in either the glucuronide or sulfated conjugated form, steroids must first undergo deconjugation followed by derivatisation to render them suitable for GC analysis. Discussed herein are the(More)
A method is presented for the routine, rapid, and quantitative analysis of aliphatic and naphthenic acids in crude oils, based on their isolation using nonaqueous ion exchange solid-phase extraction cartridges. The isolated acid fractions are methylated and analyzed by gas chromatography and gas chromatography/mass spectrometry. The method is effective on(More)
The effect of biochar addition on the levels of black carbon (BC) and polcyclic aromatic hydrocarbons (PAHs) in a vineyard soil in central Italy was investigated within a two year period. Hydropyrolysis (HyPy) was used to determine the contents of BC (BCHyPy) in the amended and control soils, while the hydrocarbon composition of the semi-labile (non-BCHyPy)(More)
An introduction to conjugated steroids and the justification for their analysis is provided covering both environmental and biological samples. Determining conjugated steroids or indeed any organic chemical which is conjugated upon excretion from the body has relevance in diagnostic monitoring, forensic screening and environmental analysis (from the(More)
The carbonaceous chondrite meteorites are fragments of asteroids that have remained relatively unprocessed since the formation of the Solar System 4.56 billion years ago. The major organic component in these meteorites is a macromolecular phase that is resistant to solvent extraction. The information contained within macromolecular material can be accessed(More)
Studies of biological molecules such as fatty acids and the steroid hormones have the potential to benefit enormously from stable carbon isotope ratio measurements of individual molecules. In their natural form, however, the body's molecules interact too readily with laboratory equipment designed to separate them for accurate measurements to be made. Some(More)
Compound-specific stable carbon isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry is an effective and risk-free means of investigating fatty acid metabolism. Straightforward analysis, however, leads to poor chromatographic resolution, while derivatization adds carbon thereby corrupting the starting stable isotopic(More)
Compound-specific stable carbon isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry is an important method for the detection of steroid abuse in athletes. However, steroids in their natural form exhibit poor chromatographic resolution, while derivatization adds carbon thereby corrupting the starting stable isotopic composition.(More)
Catalytic hydropyrolysis performed in a fixed bed reactor using high hydrogen gas pressures (>10 MPa) has the unique ability to release high yields of biomarker hydrocarbons from macromolecular organic fractions in petroleum source rocks and crude oils whilst minimising alteration to their isomeric distributions. One potential application of such bound(More)