Andy Phillips - Academia.edu (original) (raw)

Papers by Andy Phillips

Research paper thumbnail of Author response for "Authenticating bioplastics using carbon and hydrogen stable isotopes - An alternative analytical approach

Research paper thumbnail of Tracing the sources of nitrate using isotopes: 10 years of progress for New Zealand freshwater

IntroductionThe use of nitrogen and oxygen isotopes in nitrate (δ15N-NO3 and δ18O-NO3, respective... more IntroductionThe use of nitrogen and oxygen isotopes in nitrate (δ15N-NO3 and δ18O-NO3, respectively) has developed over the past 30 years to provide powerful tracer value, identifying sources and tracking processes related to nitrogen fluxes through the atmosphere, biosphere and hydrosphere. Globally, the high δ18O-NO3 values associated with atmospheric sources and oxidation processes has been most powerful in source identification for polluted northern hemisphere regions.In these regions, the signal in δ18O-NO3 is immense but highly variable, and therefore obscures nuanced studies of nitrogen cycling. Over a decade of intensive New Zealand studies have shown signatures dominated by nitrogen cycle processes without substantial atmospheric inputs, therefore offering unique potential to drill into the detail of controls on ecosystem nitrogen retention.<br>MethodsA range of programmes and activities have collected nitrate isotope samples with a 100 mL target size, preserved for i...

Research paper thumbnail of Stable isotopic characterization of analgesic drugs

Pharmaceutical …, 2004

he establishment of chemical homogeneity is a critical goal in manufacturing drug substances and ... more he establishment of chemical homogeneity is a critical goal in manufacturing drug substances and drug products, which are collectively referred to as pharmaceutical components. By contrast, manufacturers make no known effort to control these substances' and products' stable isotopic compositions. Because stable isotopes typically are used to characterize the natural materials' origins (1-8), it seems plausible that stable isotopes can be used to quantitatively characterize, or fingerprint, individual pharmaceutical batches because they ultimately are derived from natural materials. In fact, this practice and other forensic techniques were topics of particular interest at the recent American Chemical Society's "Pharmaceutical Authentication and Forensic Analysis" meeting in Tampa, Florida (9). Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products and pharmaceutical companies' economic well-being. The article explores the potential use of bulk isotopic analyses as a highly specific means to characterize products as they leave the manufacturer and are distributed on the market. The characterization of a product's ambient batch-to-batch stable isotopic variation can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. Many fields use isotopic fingerprints to quantitatively characterize various materials (8). Analyzing a wide range of stable isotopes multiplies a given material's specificity of characterization. In cases in which two or more isotopes in a given material are largely independent of each other, specificity (i.e., the ability to differentiate among sources) can be estimated as the product of the analyzed, individual isotopes' dynamic ranges (observed range/1 analytical variability). To test for the isotopic variability required to fingerprint ethical pharmaceutical components, the carbon-, oxygen-, and hydrogen-isotopic composition of four over-the-counter analgesic drug products were examined. Experimental Samples. The analyzed samples consisted of four commercially available analgesics: two types of acetaminophen and two types of aspirin (see Table Ia-b). The samples were purchased over

Research paper thumbnail of A national isotope survey to define the sources of nitrate contamination in New Zealand freshwaters

Research paper thumbnail of Authentication of Indonesian Coconut Sugar Using Stable Carbon Isotopes

Food Analytical Methods, 2021

Indonesian coconut sugar (n = 109 samples) from different local producers was analyzed over a 2-y... more Indonesian coconut sugar (n = 109 samples) from different local producers was analyzed over a 2-year period. A mean δ13C value of − 25.6‰ ± 0.4‰ was determined for unadulterated (pure) coconut sugar. Seasonal climatic differences of up to ± 0.4‰ increase the standard deviations of coconut sugar (− 25.6‰ ± 0.8‰). Up to 5% w/v of cane sugar is often added during production for seeding purposes which could increase the final coconut sugar δ13C values by up to 0.7‰. Excess C4 sugar (cane or corn sugar) was suggested in 31 coconut sugar samples due to more positive δ13C values (> − 24.8‰). More negative coconut sugar δ13C values (< − 26.4‰) may indicate additives, such as mangosteen sap, commonly used to prevent fermentation of the sugar syrup. A maximum acceptable δ13C value of − 24.1‰ for coconut sugar is proposed which cumulatively accounts for climatic variability and accepted industry seeding practices.

Research paper thumbnail of Climatic and environmental changes across the early Eocene climatic optimum at mid-Waipara River, Canterbury Basin, New Zealand

Earth-Science Reviews, 2019

The Cretaceous-Paleogene marine sedimentary succession exposed in the banks of the middle reaches... more The Cretaceous-Paleogene marine sedimentary succession exposed in the banks of the middle reaches of the Waipara River (referred to as mid-Waipara), north Canterbury, New Zealand, has been the subject of several high-profile studies of Paleogene paleoclimate over the past decade. It is one of relatively few sections globally where a multi-proxy approach is possible due to the good preservation of microfossils and organic biomarkers. The Eocene section is also well dated by magnetostratigraphy and biostratigraphy based on planktic foraminifera, calcareous nannofossils and dinoflagellate cysts (dinocysts). Here, we build on this previous work and undertake a comprehensive analysis of paleontological and geochemical indicators of climatic and environmental changes through the earlymiddle Eocene part of the section, with particular focus on the Early Eocene Climatic Optimum (EECO; 53.26-49.14 Ma). We correlate a 33.5 m-thick interval with the EECO, based on biostratigraphy, magnetostratigraphy, TEX86-paleothermometry and bulk carbonate δ 13 C. Our new sea-surface temperature (SST) record based on TEX86 agrees with a previous lower resolution record based on TEX86 and planktic foraminiferal δ 18 O and Mg/Ca ratios. The EECO interval in this section extends from the upper part of the New Zealand Waipawan Stage to the Mangaorapan/Heretaungan Stage boundary at 49.27 Ma. The EECO onset is not exposed, but the termination is well constrained by a fall in SST and shift to more positive δ 13 C values. Six negative carbon isotope excursions (CIEs) are recognised within the EECO and are tentatively correlated with CIEs J/K, M, O, Q, T and C22nH4 in the global δ 13 C compilation. The CIEs are associated with warmer SSTs, indicating that they represent hyperthermals. The BAYSPAR TEX86 calibration indicates SST increased by as much as 12°C from the early Eocene (~55 Ma) to the EECO, where SST peaked at 35°C. SST gradually declined from mid EECO (~51 Ma) into the middle Eocene. The marked warming in the early EECO is associated with the highest abundance of warm-water taxa in calcareous nannofossil and dinocyst assemblages, the highest proportion of planktic foraminifera, and a coeval long-term shift to abundant angiosperm vegetation, primarily driven by a rise in Casuarinaceae. There is good agreement between TEX86 and marine microfossil-based proxies for temperature, providing confidence that both approaches are useful guides to past water temperature. Warm-water marine taxa are most abundant in P a g e 3 | 48 the EECO but are not dominant. Comparison of the abundance of nannofossil warm-water taxa between mid-Waipara and a low-latitude site on Shatsky Rise suggests the latitudinal temperature gradient between mid-and low-latitudes in the EECO was greater than the TEX86 proxy implies. There is no clear evidence for enhanced sedimentation rates associated with the EECO, in contrast to evidence from the nearby Mead Stream section. Superabundant Homotryblium, a euryhaline dinocyst, in the early and middle EECO suggests elevated salinity and/or stratified surface waters, and there is no clear evidence of increased surface productivity associated with the EECO. Declining SST in the late EECO, ~50 Ma, corresponds with an increase in cool-water taxa and terrigenous material. This article highlights the importance of combining well-calibrated paleontological and geochemical records to better constrain and understand past warm climate states.

Research paper thumbnail of Onset of the Paleocene–Eocene Thermal Maximum in the southern Pacific Ocean (DSDP Site 277, Campbell Plateau)

Climate of the Past Discussions, 2015

Re-examination of a sediment core collected by the Deep Sea Drilling Project (DSDP Site 277) on t... more Re-examination of a sediment core collected by the Deep Sea Drilling Project (DSDP Site 277) on the western margin of the Campbell Plateau, Southwest Pacific Ocean (paleolatitude of ∼ 65 • S), has identified an intact Paleocene-Eocene (P-E) boundary overlain by a 34 cm-thick record of the initial phase of the Paleocene-Eocene Thermal Maximum (PETM) within nannofossil chalk. The upper part of the PETM is truncated, either due to drilling disturbance or a sedimentary hiatus. An intact record of the onset of the PETM is indicated by a gradual decrease in δ 13 C values over 20 cm, followed by a 14 cm interval in which δ 13 C is 2 ‰ lighter than uppermost Paleocene values. After accounting for effects of diagenetic alteration, we use δ 18 O and Mg/Ca values from foraminiferal tests to determine that intermediate and surface waters warmed by ∼ 6 • at the onset of the PETM prior to the full development of the negative δ 13 C excursion. After this initial warming, sea temperatures were relatively stable through the PETM, but declined abruptly across the unconformity that truncates the event at this site. Mg/Ca analysis of foraminiferal tests indicate peak intermediate and surface water temperatures of ∼ 19 and ∼ 32 • C, respectively. These temperatures may be influenced by enhanced poleward ocean heat transport during the PETM and surface water values may also be biased towards warm season temperatures.

Research paper thumbnail of Use of Stable Isotopes to Characterise New Zealand Butter in a Global Market

Research paper thumbnail of Authenticating bioplastics using carbon and hydrogen stable isotopes – An alternative analytical approach

Rapid Communications in Mass Spectrometry, 2021

RATIONALE A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon co... more RATIONALE A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon content (% C) was evaluated as a rapid, low-cost analytical approach to authenticate bioplastics, complementing existing radiocarbon (14 C) and Fourier transform-infrared (FTIR) analytical methods. METHODS Petroleum- and bio-based precursor materials and in-market plastics were analysed and their δ13 C, δ2 H and % C values were used to establish isotope criteria to evaluate plastic claims, and the source and biocontent of the samples. 14 C was used to confirm the findings of the isotope approach and FTIR was used to vertify the plastic type of the in-market plastics. RESULTS Distinctive carbon and hydrogen stable isotope ratios were found for authentic bio-based and petroleum-based precursor plastics, and it was possible to classify in-market plastics according to their source materials (petroleum, C3, C4, and mixed sources). An estimation of C4 biocontent was possible from a C4-petroleum isotope mixing model using δ13 C which was well-correlated (R2 =0.98) to 14 C. It was not possible to establish a C3-petroleum isotope mixing model due to δ13 C isotopic overlap with petroleum plastics; however, the additon of δ2 H and % C was useful to evaluate if petroleum-bioplastic mixes contained C3 bioplastics, and PLS-DA modelling reliably clustered each plastic type. CONCLUSIONS A combined dual stable isotope and carbon content approach was found to rapidly and accurately identify C3 and C4 bio-based products from their petroleum counterparts, and identify instances of petroleum and bio-based mixes frequently found in mislabelled bioplastics. Eighteen out of thirty seven in-market products labelled as bioplastic were found to contain varying amounts of petroleum-based plastic and did not meet their bio-based claims.

Research paper thumbnail of Calculating uncertainty for the RICE ice core continuous flow analysis water isotope record

Atmospheric Measurement Techniques

We describe a systematic approach to the calibration and uncertainty estimation of a high-resolut... more We describe a systematic approach to the calibration and uncertainty estimation of a high-resolution continuous flow analysis (CFA) water isotope (δ 2 H, δ 18 O) record from the Roosevelt Island Climate Evolution (RICE) Antarctic ice core. Our method establishes robust uncertainty estimates for CFA δ 2 H and δ 18 O measurements, comparable to those reported for discrete sample δ 2 H and δ 18 O analysis. Data were calibrated using a time-weighted two-point linear calibration with two standards measured both before and after continuously melting 3 or 4 m of ice core. The error at each data point was calculated as the quadrature sum of three factors: Allan variance error, scatter over our averaging interval (error of the variance) and calibration error (error of the mean). Final mean total uncertainty for the entire record is δ 2 H = 0.74 ‰ and δ 18 O = 0.21 ‰. Uncertainties vary through the data set and were exacerbated by a range of factors, which typically could not be isolated due to the requirements of the multi-instrument CFA campaign. These factors likely occurred in combination and included ice quality, ice breaks, upstream equipment failure, contamination with drill fluid and leaks or valve degradation. We demonstrate that our methodology for documenting uncertainty was effective across periods of uneven system performance and delivered a significant achievement in the precision of highresolution CFA water isotope measurements.

Research paper thumbnail of Integrating Continuous-Flow Mass Spectrometry and Automatic CO2 Collection for AMS

Radiocarbon

Accelerator mass spectrometry (AMS) radiocarbon measurements of organic samples require combustio... more Accelerator mass spectrometry (AMS) radiocarbon measurements of organic samples require combustion to obtain CO2 for graphitization. Furthermore, determination of δ13C values is required in order to correct the 14C age due to carbon isotope fractionation effects. δ13C analysis is commonly carried out by stable isotope mass spectrometry because most applications demand high-precision δ13C values in addition to the requirements of 14C dating. A simplifying step is therefore to combine the combustion for stable isotope analysis with cryogenic trapping of CO2 for AMS graphite targets. Presented here is a simple CO2 trapping device based on a modified Gilson 220XL sampling (manifold) robot coupled to the inlet manifold system of a GV Instruments IsoPrime stable isotope mass spectrometer. The system is capable of batch combustion and analysis of up to 40 samples and is under full computer control by the mass spectrometer software. All trapping parameters such as flush time prior to trappi...

Research paper thumbnail of The onset of the Early Eocene Climatic Optimum at Branch Stream, Clarence River valley, New Zealand

New Zealand Journal of Geology and Geophysics, 2015

Research paper thumbnail of High-speed narrow-bore capillary gas chromatography in combination with a fast double-focusing mass spectrometer

Journal of High Resolution Chromatography, 1995

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of Screening urine for exogenous testosterone by isotope ratio mass spectrometric analysis of one pregnanediol and two androstanediols

Journal of Chromatography B: Biomedical Sciences and Applications, 1999

We propose a new screening method for testosterone (T) doping in sport. The current method for de... more We propose a new screening method for testosterone (T) doping in sport. The current method for detecting T administration is based on finding a T to epitestosterone ratio (T/E) in urine that exceeds six. The difficulties with T/E are that T administration does not always result in a T/E&gt;6 and that a rare individual will have T/E&gt;6 in the absence of T administration. Our previous studies reveal that carbon isotope ratio helps to determine the origin of the urinary T because the values for T and its metabolites decrease after the administration of exogenous T. In this study, we present a rapid and efficient screening sample preparation method based on three successive liquid-solid extractions, deconjugation with E. coli beta-glucuronidase after the first extraction, acetylation after the second extraction, and a final extraction of the acetates. The 13C/12C of two T metabolites (5beta-androstane-3alpha,17beta-diol and 5alpha-androstane-3alpha,17beta-diol) and one pregnanediol as endogenous reference (5beta-pregnane-3alpha,20alpha-diol) was measured by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) on 10 ml of urine collected from 10 healthy men before and after T administration. Following T administration, the 13 C/12C of 5beta-androstane-3alpha,17beta-diol diacetate and 5alpha-androstane-3alpha,17beta-diol diacetate declined significantly from -26.2 per thousand to -30.8 per thousand and from -25.2 per thousand to -29.9 per thousand, respectively and the 13C/12C of 5beta-pregnane-3alpha,20alpha-diol diacetate was unchanged. In addition, the ratio of androstanediols to pregnanediol increased in the post-T urines.

Research paper thumbnail of Confirming testosterone administration by isotope ratio mass spectrometric analysis of urinary androstanediols

Steroids, 1997

A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for... more A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for studying the incorporation of exogenous testosterone enanthate into excreted urinary 5or-and 515-androstane-3c~,176diols. A multistep but straigh(forward work-up procedure produced a simple GC chromatogram of urina~ steroid acetates composed principally of two androstanediols and pregnanedioL It is anticipated that such a method may form the basis of a doping control test for testosterone that could be used as a primary method during major sporting events or alternatively as a verification technique. Urine samples from five individuals were collected before and after administration of testosterone enanthate (250 rag). The ~/3C °/00 value of androstanediols was around-26 to-28 during the baseline period and decreased to about-29 to-30 in the days following synthetic testosterone administration. One of the other major steroids in the chromatogram, pregnanediol, was utilized as the "internal standard," because its ~13C°/00 values did not markedly change following testosterone administration, remaining at-25 to-27. In all subjects studied, the ~13C°/00 values for androstanediols were reduced sufficiently over 8 days to confirm administration of synthetic testosterone. Although steroids isolated from urine of normal individuals from 12 different countries gave values between-24 and-28, this seemed not to be related to nationality or region. The most likely variable is the proportion of plants with low and high carbon 13 content in the diet. This variable is likely to be more affected by individual food preferences than broad ethnic food divisions. In this paper, we propose a ratio of ~13 C°/OO for androstanediols to pregnanediol as a useful discriminant of testosterone misuse, a value above 1.1:1.0 being indicative of such misuse. The work-up procedure was designed for batch analysis and to use only simple techniques, rather than employ further instrumentation, such as high-performance liquid chromatography (HPLC), in purifying steroids for GC/C/IRMS.

Research paper thumbnail of Androstanediol and 5-androstenediol profiling for detecting exogenously administered dihydrotestosterone, epitestosterone, and dehydroepiandrosterone: Potential use in gas chromatography isotope ratio mass spectrometry

Steroids, 1997

The basis of a potential method for confirming intake of four natural androgens (testosterone, ep... more The basis of a potential method for confirming intake of four natural androgens (testosterone, epitestosterone, dihydrotestosterone, and dehydroepiandrosterone is presented. The method relies on isolating from urine a steroid fraction containing androstenediol and androstanediol metabolites of these natural steroids" and analyzing their ~~C content by gas chromatography, combustion, isotope ratio mass spectrometry. The steroids were recovered from urine by conjugate hydrolysis with a Helix pomatia preparation (sulfatase and [3-glucuronidase), Girard T reagent separation to obtain a nonketonic fraction, and Sephadex LH-20 chromatography for purtfication. Metabolites appropriate for all of the natural steroids could be separated (as diacetates) by gas chromatography on a DB-17 capillary column viz.: 5o~ (and [3)-androstane-3c~,17c~-diol (epitestosterone as precursor); 5t~ (and [3)-androstane-3e~,17[3-diol (testosterone as precursor); 5-androstene-3[3,17[3-diol (dehydroepiandrosterone precursor); and 5c~-androstane-3ct, 1713-(and 17c¢-) diol (dihydrotestosterone precursor). Measurement of the ~~ C content of the specific analytes after ingestion of the androgen precursors demonstrated a lowering of 8L~C%c value compared to normal values. Typically, in the male individual studied, 313C%~ values for all components were-26 to-27 before drug administration and-29 to-30 at 6 h qfter, the latter values reflecting those obtaining for commercial synthetic steroid compared to in vivo synthesized steroid. While generally the metabolism of the steroids" was as expected, this was not the case for 5ct-dihydrotestosterone. A mqjor metabolite was 5c~-androstane-3o~, 17c~-diol, which had presumably been formed by 1713/I 7c~ isomerization, a process previously known for unnatural anabolics but not for natural hormones. The isolation, purification, and isotope ratio mass spectrometry techniques described may form the basis of a general method for confirming natural steroid misuse by sports participants.

Research paper thumbnail of Investigating C-4 Sugar Contamination of Manuka Honey and Other New Zealand Honey Varieties Using Carbon Isotopes

Journal of Agricultural and Food Chemistry, 2014

Carbon isotopes (δ(13)C honey and δ(13)C protein) and apparent C-4 sugar contents of 1023 New Zea... more Carbon isotopes (δ(13)C honey and δ(13)C protein) and apparent C-4 sugar contents of 1023 New Zealand honeys from 15 different floral types were analyzed to investigate which New Zealand honey is prone to failing the AOAC 998.12 C-4 sugar test and evaluate the occurrence of false-positive results. Of the 333 honey samples that exceeded the 7% C-4 sugar threshold, 324 samples of these were New Zealand manuka honey (Leptospermum scoparium, 97.2% of all fails found in the study). Three monofloral honeys (ling, kamahi, and tawari) had nine samples (2.8% of all fails found in the study) with apparent C-4 sugars exceeding 7%. All other floral types analyzed did not display C-4 sugar fails. False-positive results were found to occur for higher activity New Zealand manuka honey with a methylglyoxal content &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;250 mg/kg or a nonperoxide activity &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10+, and for some ling, kamahi and tawari honeys. Recommendations for future interpretation of the AOAC 998.12 C-4 sugar method are proposed.

Research paper thumbnail of Organic-rich sedimentation in the South Pacific Ocean associated with Late Paleocene climatic cooling

Earth-Science Reviews, 2014

A distinctive organic-rich marine mudstone of Late Paleocene age occurs in most of New Zealand's ... more A distinctive organic-rich marine mudstone of Late Paleocene age occurs in most of New Zealand's sedimentary basins and has been identified as a potential source rock for oil and gas. Identified as the Waipawa Formation in the East Coast Basin and the Tartan Formation in the Great South and Canterbury Basins, the unit is a relatively uniform massive mudstone that varies greatly in thickness (2-70 m) and grades laterally into distinctive facies equivalents, notably greensand and a thin-bedded siliceous mudstone. All these facies are characterised by relatively high TOC (0.5-10 wt.%) and 13 C enrichment (δ 13 C TOC N − 24‰), and we refer to them collectively as "Waipawa organofacies". Our detailed stratigraphic and geochemical studies refine the age (58.7 to 59.4 Ma), distribution and nature of the Waipawa organofacies. We have determined that deposition occurred in continental margin settings throughout much of the southwest Pacific under cool, dysoxic conditions associated with a significant influx of terrestrial organic matter, high marine productivity, a global fall in sea level, and a regional unconformity across shallow and deep marine settings. The combination of cool temperatures, lowered sea level and bathyal erosion suggests that deposition was linked to short-lived growth of an Antarctic ice sheet in the earliest Late Paleocene (~59 Ma).

Research paper thumbnail of Confirming Testosterone Administration by Isotope Ratio Mass Spectrometric Analysis of Urinary Androstanediols

Steroids, 1997

A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for... more A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for studying the incorporation of exogenous testosterone enanthate into excreted urinary 5α-and 5β-androstane-3α,17β-diols. A multistep but straightforward work-up procedure ...

Research paper thumbnail of Author response for "Authenticating bioplastics using carbon and hydrogen stable isotopes - An alternative analytical approach

Research paper thumbnail of Tracing the sources of nitrate using isotopes: 10 years of progress for New Zealand freshwater

IntroductionThe use of nitrogen and oxygen isotopes in nitrate (δ15N-NO3 and δ18O-NO3, respective... more IntroductionThe use of nitrogen and oxygen isotopes in nitrate (δ15N-NO3 and δ18O-NO3, respectively) has developed over the past 30 years to provide powerful tracer value, identifying sources and tracking processes related to nitrogen fluxes through the atmosphere, biosphere and hydrosphere. Globally, the high δ18O-NO3 values associated with atmospheric sources and oxidation processes has been most powerful in source identification for polluted northern hemisphere regions.In these regions, the signal in δ18O-NO3 is immense but highly variable, and therefore obscures nuanced studies of nitrogen cycling. Over a decade of intensive New Zealand studies have shown signatures dominated by nitrogen cycle processes without substantial atmospheric inputs, therefore offering unique potential to drill into the detail of controls on ecosystem nitrogen retention.<br>MethodsA range of programmes and activities have collected nitrate isotope samples with a 100 mL target size, preserved for i...

Research paper thumbnail of Stable isotopic characterization of analgesic drugs

Pharmaceutical …, 2004

he establishment of chemical homogeneity is a critical goal in manufacturing drug substances and ... more he establishment of chemical homogeneity is a critical goal in manufacturing drug substances and drug products, which are collectively referred to as pharmaceutical components. By contrast, manufacturers make no known effort to control these substances' and products' stable isotopic compositions. Because stable isotopes typically are used to characterize the natural materials' origins (1-8), it seems plausible that stable isotopes can be used to quantitatively characterize, or fingerprint, individual pharmaceutical batches because they ultimately are derived from natural materials. In fact, this practice and other forensic techniques were topics of particular interest at the recent American Chemical Society's "Pharmaceutical Authentication and Forensic Analysis" meeting in Tampa, Florida (9). Counterfeiting of pharmaceutical drugs threatens consumer confidence in drug products and pharmaceutical companies' economic well-being. The article explores the potential use of bulk isotopic analyses as a highly specific means to characterize products as they leave the manufacturer and are distributed on the market. The characterization of a product's ambient batch-to-batch stable isotopic variation can be used to differentiate among individual drug batches and subsequently identify counterfeits on the market. Many fields use isotopic fingerprints to quantitatively characterize various materials (8). Analyzing a wide range of stable isotopes multiplies a given material's specificity of characterization. In cases in which two or more isotopes in a given material are largely independent of each other, specificity (i.e., the ability to differentiate among sources) can be estimated as the product of the analyzed, individual isotopes' dynamic ranges (observed range/1 analytical variability). To test for the isotopic variability required to fingerprint ethical pharmaceutical components, the carbon-, oxygen-, and hydrogen-isotopic composition of four over-the-counter analgesic drug products were examined. Experimental Samples. The analyzed samples consisted of four commercially available analgesics: two types of acetaminophen and two types of aspirin (see Table Ia-b). The samples were purchased over

Research paper thumbnail of A national isotope survey to define the sources of nitrate contamination in New Zealand freshwaters

Research paper thumbnail of Authentication of Indonesian Coconut Sugar Using Stable Carbon Isotopes

Food Analytical Methods, 2021

Indonesian coconut sugar (n = 109 samples) from different local producers was analyzed over a 2-y... more Indonesian coconut sugar (n = 109 samples) from different local producers was analyzed over a 2-year period. A mean δ13C value of − 25.6‰ ± 0.4‰ was determined for unadulterated (pure) coconut sugar. Seasonal climatic differences of up to ± 0.4‰ increase the standard deviations of coconut sugar (− 25.6‰ ± 0.8‰). Up to 5% w/v of cane sugar is often added during production for seeding purposes which could increase the final coconut sugar δ13C values by up to 0.7‰. Excess C4 sugar (cane or corn sugar) was suggested in 31 coconut sugar samples due to more positive δ13C values (> − 24.8‰). More negative coconut sugar δ13C values (< − 26.4‰) may indicate additives, such as mangosteen sap, commonly used to prevent fermentation of the sugar syrup. A maximum acceptable δ13C value of − 24.1‰ for coconut sugar is proposed which cumulatively accounts for climatic variability and accepted industry seeding practices.

Research paper thumbnail of Climatic and environmental changes across the early Eocene climatic optimum at mid-Waipara River, Canterbury Basin, New Zealand

Earth-Science Reviews, 2019

The Cretaceous-Paleogene marine sedimentary succession exposed in the banks of the middle reaches... more The Cretaceous-Paleogene marine sedimentary succession exposed in the banks of the middle reaches of the Waipara River (referred to as mid-Waipara), north Canterbury, New Zealand, has been the subject of several high-profile studies of Paleogene paleoclimate over the past decade. It is one of relatively few sections globally where a multi-proxy approach is possible due to the good preservation of microfossils and organic biomarkers. The Eocene section is also well dated by magnetostratigraphy and biostratigraphy based on planktic foraminifera, calcareous nannofossils and dinoflagellate cysts (dinocysts). Here, we build on this previous work and undertake a comprehensive analysis of paleontological and geochemical indicators of climatic and environmental changes through the earlymiddle Eocene part of the section, with particular focus on the Early Eocene Climatic Optimum (EECO; 53.26-49.14 Ma). We correlate a 33.5 m-thick interval with the EECO, based on biostratigraphy, magnetostratigraphy, TEX86-paleothermometry and bulk carbonate δ 13 C. Our new sea-surface temperature (SST) record based on TEX86 agrees with a previous lower resolution record based on TEX86 and planktic foraminiferal δ 18 O and Mg/Ca ratios. The EECO interval in this section extends from the upper part of the New Zealand Waipawan Stage to the Mangaorapan/Heretaungan Stage boundary at 49.27 Ma. The EECO onset is not exposed, but the termination is well constrained by a fall in SST and shift to more positive δ 13 C values. Six negative carbon isotope excursions (CIEs) are recognised within the EECO and are tentatively correlated with CIEs J/K, M, O, Q, T and C22nH4 in the global δ 13 C compilation. The CIEs are associated with warmer SSTs, indicating that they represent hyperthermals. The BAYSPAR TEX86 calibration indicates SST increased by as much as 12°C from the early Eocene (~55 Ma) to the EECO, where SST peaked at 35°C. SST gradually declined from mid EECO (~51 Ma) into the middle Eocene. The marked warming in the early EECO is associated with the highest abundance of warm-water taxa in calcareous nannofossil and dinocyst assemblages, the highest proportion of planktic foraminifera, and a coeval long-term shift to abundant angiosperm vegetation, primarily driven by a rise in Casuarinaceae. There is good agreement between TEX86 and marine microfossil-based proxies for temperature, providing confidence that both approaches are useful guides to past water temperature. Warm-water marine taxa are most abundant in P a g e 3 | 48 the EECO but are not dominant. Comparison of the abundance of nannofossil warm-water taxa between mid-Waipara and a low-latitude site on Shatsky Rise suggests the latitudinal temperature gradient between mid-and low-latitudes in the EECO was greater than the TEX86 proxy implies. There is no clear evidence for enhanced sedimentation rates associated with the EECO, in contrast to evidence from the nearby Mead Stream section. Superabundant Homotryblium, a euryhaline dinocyst, in the early and middle EECO suggests elevated salinity and/or stratified surface waters, and there is no clear evidence of increased surface productivity associated with the EECO. Declining SST in the late EECO, ~50 Ma, corresponds with an increase in cool-water taxa and terrigenous material. This article highlights the importance of combining well-calibrated paleontological and geochemical records to better constrain and understand past warm climate states.

Research paper thumbnail of Onset of the Paleocene–Eocene Thermal Maximum in the southern Pacific Ocean (DSDP Site 277, Campbell Plateau)

Climate of the Past Discussions, 2015

Re-examination of a sediment core collected by the Deep Sea Drilling Project (DSDP Site 277) on t... more Re-examination of a sediment core collected by the Deep Sea Drilling Project (DSDP Site 277) on the western margin of the Campbell Plateau, Southwest Pacific Ocean (paleolatitude of ∼ 65 • S), has identified an intact Paleocene-Eocene (P-E) boundary overlain by a 34 cm-thick record of the initial phase of the Paleocene-Eocene Thermal Maximum (PETM) within nannofossil chalk. The upper part of the PETM is truncated, either due to drilling disturbance or a sedimentary hiatus. An intact record of the onset of the PETM is indicated by a gradual decrease in δ 13 C values over 20 cm, followed by a 14 cm interval in which δ 13 C is 2 ‰ lighter than uppermost Paleocene values. After accounting for effects of diagenetic alteration, we use δ 18 O and Mg/Ca values from foraminiferal tests to determine that intermediate and surface waters warmed by ∼ 6 • at the onset of the PETM prior to the full development of the negative δ 13 C excursion. After this initial warming, sea temperatures were relatively stable through the PETM, but declined abruptly across the unconformity that truncates the event at this site. Mg/Ca analysis of foraminiferal tests indicate peak intermediate and surface water temperatures of ∼ 19 and ∼ 32 • C, respectively. These temperatures may be influenced by enhanced poleward ocean heat transport during the PETM and surface water values may also be biased towards warm season temperatures.

Research paper thumbnail of Use of Stable Isotopes to Characterise New Zealand Butter in a Global Market

Research paper thumbnail of Authenticating bioplastics using carbon and hydrogen stable isotopes – An alternative analytical approach

Rapid Communications in Mass Spectrometry, 2021

RATIONALE A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon co... more RATIONALE A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon content (% C) was evaluated as a rapid, low-cost analytical approach to authenticate bioplastics, complementing existing radiocarbon (14 C) and Fourier transform-infrared (FTIR) analytical methods. METHODS Petroleum- and bio-based precursor materials and in-market plastics were analysed and their δ13 C, δ2 H and % C values were used to establish isotope criteria to evaluate plastic claims, and the source and biocontent of the samples. 14 C was used to confirm the findings of the isotope approach and FTIR was used to vertify the plastic type of the in-market plastics. RESULTS Distinctive carbon and hydrogen stable isotope ratios were found for authentic bio-based and petroleum-based precursor plastics, and it was possible to classify in-market plastics according to their source materials (petroleum, C3, C4, and mixed sources). An estimation of C4 biocontent was possible from a C4-petroleum isotope mixing model using δ13 C which was well-correlated (R2 =0.98) to 14 C. It was not possible to establish a C3-petroleum isotope mixing model due to δ13 C isotopic overlap with petroleum plastics; however, the additon of δ2 H and % C was useful to evaluate if petroleum-bioplastic mixes contained C3 bioplastics, and PLS-DA modelling reliably clustered each plastic type. CONCLUSIONS A combined dual stable isotope and carbon content approach was found to rapidly and accurately identify C3 and C4 bio-based products from their petroleum counterparts, and identify instances of petroleum and bio-based mixes frequently found in mislabelled bioplastics. Eighteen out of thirty seven in-market products labelled as bioplastic were found to contain varying amounts of petroleum-based plastic and did not meet their bio-based claims.

Research paper thumbnail of Calculating uncertainty for the RICE ice core continuous flow analysis water isotope record

Atmospheric Measurement Techniques

We describe a systematic approach to the calibration and uncertainty estimation of a high-resolut... more We describe a systematic approach to the calibration and uncertainty estimation of a high-resolution continuous flow analysis (CFA) water isotope (δ 2 H, δ 18 O) record from the Roosevelt Island Climate Evolution (RICE) Antarctic ice core. Our method establishes robust uncertainty estimates for CFA δ 2 H and δ 18 O measurements, comparable to those reported for discrete sample δ 2 H and δ 18 O analysis. Data were calibrated using a time-weighted two-point linear calibration with two standards measured both before and after continuously melting 3 or 4 m of ice core. The error at each data point was calculated as the quadrature sum of three factors: Allan variance error, scatter over our averaging interval (error of the variance) and calibration error (error of the mean). Final mean total uncertainty for the entire record is δ 2 H = 0.74 ‰ and δ 18 O = 0.21 ‰. Uncertainties vary through the data set and were exacerbated by a range of factors, which typically could not be isolated due to the requirements of the multi-instrument CFA campaign. These factors likely occurred in combination and included ice quality, ice breaks, upstream equipment failure, contamination with drill fluid and leaks or valve degradation. We demonstrate that our methodology for documenting uncertainty was effective across periods of uneven system performance and delivered a significant achievement in the precision of highresolution CFA water isotope measurements.

Research paper thumbnail of Integrating Continuous-Flow Mass Spectrometry and Automatic CO2 Collection for AMS

Radiocarbon

Accelerator mass spectrometry (AMS) radiocarbon measurements of organic samples require combustio... more Accelerator mass spectrometry (AMS) radiocarbon measurements of organic samples require combustion to obtain CO2 for graphitization. Furthermore, determination of δ13C values is required in order to correct the 14C age due to carbon isotope fractionation effects. δ13C analysis is commonly carried out by stable isotope mass spectrometry because most applications demand high-precision δ13C values in addition to the requirements of 14C dating. A simplifying step is therefore to combine the combustion for stable isotope analysis with cryogenic trapping of CO2 for AMS graphite targets. Presented here is a simple CO2 trapping device based on a modified Gilson 220XL sampling (manifold) robot coupled to the inlet manifold system of a GV Instruments IsoPrime stable isotope mass spectrometer. The system is capable of batch combustion and analysis of up to 40 samples and is under full computer control by the mass spectrometer software. All trapping parameters such as flush time prior to trappi...

Research paper thumbnail of The onset of the Early Eocene Climatic Optimum at Branch Stream, Clarence River valley, New Zealand

New Zealand Journal of Geology and Geophysics, 2015

Research paper thumbnail of High-speed narrow-bore capillary gas chromatography in combination with a fast double-focusing mass spectrometer

Journal of High Resolution Chromatography, 1995

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of Screening urine for exogenous testosterone by isotope ratio mass spectrometric analysis of one pregnanediol and two androstanediols

Journal of Chromatography B: Biomedical Sciences and Applications, 1999

We propose a new screening method for testosterone (T) doping in sport. The current method for de... more We propose a new screening method for testosterone (T) doping in sport. The current method for detecting T administration is based on finding a T to epitestosterone ratio (T/E) in urine that exceeds six. The difficulties with T/E are that T administration does not always result in a T/E&gt;6 and that a rare individual will have T/E&gt;6 in the absence of T administration. Our previous studies reveal that carbon isotope ratio helps to determine the origin of the urinary T because the values for T and its metabolites decrease after the administration of exogenous T. In this study, we present a rapid and efficient screening sample preparation method based on three successive liquid-solid extractions, deconjugation with E. coli beta-glucuronidase after the first extraction, acetylation after the second extraction, and a final extraction of the acetates. The 13C/12C of two T metabolites (5beta-androstane-3alpha,17beta-diol and 5alpha-androstane-3alpha,17beta-diol) and one pregnanediol as endogenous reference (5beta-pregnane-3alpha,20alpha-diol) was measured by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) on 10 ml of urine collected from 10 healthy men before and after T administration. Following T administration, the 13 C/12C of 5beta-androstane-3alpha,17beta-diol diacetate and 5alpha-androstane-3alpha,17beta-diol diacetate declined significantly from -26.2 per thousand to -30.8 per thousand and from -25.2 per thousand to -29.9 per thousand, respectively and the 13C/12C of 5beta-pregnane-3alpha,20alpha-diol diacetate was unchanged. In addition, the ratio of androstanediols to pregnanediol increased in the post-T urines.

Research paper thumbnail of Confirming testosterone administration by isotope ratio mass spectrometric analysis of urinary androstanediols

Steroids, 1997

A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for... more A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for studying the incorporation of exogenous testosterone enanthate into excreted urinary 5or-and 515-androstane-3c~,176diols. A multistep but straigh(forward work-up procedure produced a simple GC chromatogram of urina~ steroid acetates composed principally of two androstanediols and pregnanedioL It is anticipated that such a method may form the basis of a doping control test for testosterone that could be used as a primary method during major sporting events or alternatively as a verification technique. Urine samples from five individuals were collected before and after administration of testosterone enanthate (250 rag). The ~/3C °/00 value of androstanediols was around-26 to-28 during the baseline period and decreased to about-29 to-30 in the days following synthetic testosterone administration. One of the other major steroids in the chromatogram, pregnanediol, was utilized as the "internal standard," because its ~13C°/00 values did not markedly change following testosterone administration, remaining at-25 to-27. In all subjects studied, the ~13C°/00 values for androstanediols were reduced sufficiently over 8 days to confirm administration of synthetic testosterone. Although steroids isolated from urine of normal individuals from 12 different countries gave values between-24 and-28, this seemed not to be related to nationality or region. The most likely variable is the proportion of plants with low and high carbon 13 content in the diet. This variable is likely to be more affected by individual food preferences than broad ethnic food divisions. In this paper, we propose a ratio of ~13 C°/OO for androstanediols to pregnanediol as a useful discriminant of testosterone misuse, a value above 1.1:1.0 being indicative of such misuse. The work-up procedure was designed for batch analysis and to use only simple techniques, rather than employ further instrumentation, such as high-performance liquid chromatography (HPLC), in purifying steroids for GC/C/IRMS.

Research paper thumbnail of Androstanediol and 5-androstenediol profiling for detecting exogenously administered dihydrotestosterone, epitestosterone, and dehydroepiandrosterone: Potential use in gas chromatography isotope ratio mass spectrometry

Steroids, 1997

The basis of a potential method for confirming intake of four natural androgens (testosterone, ep... more The basis of a potential method for confirming intake of four natural androgens (testosterone, epitestosterone, dihydrotestosterone, and dehydroepiandrosterone is presented. The method relies on isolating from urine a steroid fraction containing androstenediol and androstanediol metabolites of these natural steroids" and analyzing their ~~C content by gas chromatography, combustion, isotope ratio mass spectrometry. The steroids were recovered from urine by conjugate hydrolysis with a Helix pomatia preparation (sulfatase and [3-glucuronidase), Girard T reagent separation to obtain a nonketonic fraction, and Sephadex LH-20 chromatography for purtfication. Metabolites appropriate for all of the natural steroids could be separated (as diacetates) by gas chromatography on a DB-17 capillary column viz.: 5o~ (and [3)-androstane-3c~,17c~-diol (epitestosterone as precursor); 5t~ (and [3)-androstane-3e~,17[3-diol (testosterone as precursor); 5-androstene-3[3,17[3-diol (dehydroepiandrosterone precursor); and 5c~-androstane-3ct, 1713-(and 17c¢-) diol (dihydrotestosterone precursor). Measurement of the ~~ C content of the specific analytes after ingestion of the androgen precursors demonstrated a lowering of 8L~C%c value compared to normal values. Typically, in the male individual studied, 313C%~ values for all components were-26 to-27 before drug administration and-29 to-30 at 6 h qfter, the latter values reflecting those obtaining for commercial synthetic steroid compared to in vivo synthesized steroid. While generally the metabolism of the steroids" was as expected, this was not the case for 5ct-dihydrotestosterone. A mqjor metabolite was 5c~-androstane-3o~, 17c~-diol, which had presumably been formed by 1713/I 7c~ isomerization, a process previously known for unnatural anabolics but not for natural hormones. The isolation, purification, and isotope ratio mass spectrometry techniques described may form the basis of a general method for confirming natural steroid misuse by sports participants.

Research paper thumbnail of Investigating C-4 Sugar Contamination of Manuka Honey and Other New Zealand Honey Varieties Using Carbon Isotopes

Journal of Agricultural and Food Chemistry, 2014

Carbon isotopes (δ(13)C honey and δ(13)C protein) and apparent C-4 sugar contents of 1023 New Zea... more Carbon isotopes (δ(13)C honey and δ(13)C protein) and apparent C-4 sugar contents of 1023 New Zealand honeys from 15 different floral types were analyzed to investigate which New Zealand honey is prone to failing the AOAC 998.12 C-4 sugar test and evaluate the occurrence of false-positive results. Of the 333 honey samples that exceeded the 7% C-4 sugar threshold, 324 samples of these were New Zealand manuka honey (Leptospermum scoparium, 97.2% of all fails found in the study). Three monofloral honeys (ling, kamahi, and tawari) had nine samples (2.8% of all fails found in the study) with apparent C-4 sugars exceeding 7%. All other floral types analyzed did not display C-4 sugar fails. False-positive results were found to occur for higher activity New Zealand manuka honey with a methylglyoxal content &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;250 mg/kg or a nonperoxide activity &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10+, and for some ling, kamahi and tawari honeys. Recommendations for future interpretation of the AOAC 998.12 C-4 sugar method are proposed.

Research paper thumbnail of Organic-rich sedimentation in the South Pacific Ocean associated with Late Paleocene climatic cooling

Earth-Science Reviews, 2014

A distinctive organic-rich marine mudstone of Late Paleocene age occurs in most of New Zealand's ... more A distinctive organic-rich marine mudstone of Late Paleocene age occurs in most of New Zealand's sedimentary basins and has been identified as a potential source rock for oil and gas. Identified as the Waipawa Formation in the East Coast Basin and the Tartan Formation in the Great South and Canterbury Basins, the unit is a relatively uniform massive mudstone that varies greatly in thickness (2-70 m) and grades laterally into distinctive facies equivalents, notably greensand and a thin-bedded siliceous mudstone. All these facies are characterised by relatively high TOC (0.5-10 wt.%) and 13 C enrichment (δ 13 C TOC N − 24‰), and we refer to them collectively as "Waipawa organofacies". Our detailed stratigraphic and geochemical studies refine the age (58.7 to 59.4 Ma), distribution and nature of the Waipawa organofacies. We have determined that deposition occurred in continental margin settings throughout much of the southwest Pacific under cool, dysoxic conditions associated with a significant influx of terrestrial organic matter, high marine productivity, a global fall in sea level, and a regional unconformity across shallow and deep marine settings. The combination of cool temperatures, lowered sea level and bathyal erosion suggests that deposition was linked to short-lived growth of an Antarctic ice sheet in the earliest Late Paleocene (~59 Ma).

Research paper thumbnail of Confirming Testosterone Administration by Isotope Ratio Mass Spectrometric Analysis of Urinary Androstanediols

Steroids, 1997

A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for... more A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for studying the incorporation of exogenous testosterone enanthate into excreted urinary 5α-and 5β-androstane-3α,17β-diols. A multistep but straightforward work-up procedure ...