Investigating the Use of Element Analysis for Differentiation between the Geographic Origins of Western Cape Wines

The aim of this study was to differentiate between the geographic origins of wines produced in the Western Cape on the basis of their element composition. A total of 96 market-ready red and white wines (Pinotage, Shiraz, Merlot, Cabernet Sauvignon, Sauvignon blanc, Chardonnay and Chenin blanc) were analysed by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The discriminant methods: stepwise discriminant analysis, canonical discriminant analysis and linear discriminant analysis were applied to the data sets. A classification accuracy of 38% for Pinotage, 55% for Shiraz, 68% for Merlot, 75% for Cabernet Sauvignon, 93% for Sauvignon blanc, 68% for Chardonnay and 100% for Chenin blanc was achieved. Subject to the conditions of this study, it was concluded that differentiation between wines according to geographical origin was possible using the elemental composition

Volatile components of the anal gland secretion of the striped polecat Ictonyx striatus

The volatile components of the anal gland secretion of an adult, male, Ictonyx striatus were separated and identified by dynamic solvent effect sampling, capillary gas-liquid chromatography, and mass spectrometry. The major component was 2-ethylthiacyclobutane. Nine other sulphur compounds, a ketone, and a hydrocarbon were also identified. Some of these occur in the anal gland secretions of other mustelids

Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae)

The cossid moth (Coryphodema tristis) has a broad range of native tree hosts in South Africa. The moth recently moved into non-native Eucalyptus plantations in South Africa, on which it now causes significant damage. Here we investigate the chemicals involved in pheromone communication between the sexes of this moth in order to better understand its ecology, and with a view to potentially develop management tools for it. In particular, we characterize female gland extracts and headspace samples through coupled gas chromatography electro-antennographic detection (GC-EAD) and two dimensional gas chromatography mass spectrometry (GCxGC-MS). Tentative identities of the potential pheromone compounds were confirmed by comparing both retention time and mass spectra with authentic standards. Two electrophysiologically active pheromone compounds, tetradecyl acetate (14:OAc) and Z9-tetradecenyl acetate (Z9-14:OAc) were identified from pheromone gland extracts, and an additional compound (Z9-14:OH) from headspace samples. We further determined dose response curves for the identified compounds and six other structurally similar compounds that are common to the order Cossidae. Male antennae showed superior sensitivity toward Z9-14:OAc, Z7-tetradecenyl acetate (Z7-14:OAc), E9-tetradecenyl acetate (E9-14:OAc), Z9-tetradecenol (Z9-14:OH) and Z9-tetradecenal (Z9-14:Ald) when compared to female antennae. While we could show electrophysiological responses to single pheromone compounds, behavioral attraction of males was dependent on the synergistic effect of at least two of these compounds. Signal specificity is shown to be gained through pheromone blends. A field trial showed that a significant number of males were caught only in traps baited with a combination of Z9-14:OAc (circa 95 of the ratio) and Z9-14:OH. Addition of 14:OAc to this mixture also improved the number of males caught, although not significantly. This study represents a major step towards developing a useful attractant to be used in management tools for C. tristis and contributes to the understanding of chemical communication and biology of this group of insects

In-line catalytic derivatization method for selctive detection of chlorinated aromatics with a hyphenated gas chromatography/ Laser mass spectrometry technique : A concept for comprehensive detection of isomeric ensembles.

The combination of gas chromatography (GC) and laser-based resonance-enhanced multiphoton ionization-time-of-flight mass spectrometry (REMPI-TOFMS) represents a three-dimensional analytical method, using the gas chromatographic retention time, the wavelength of the ionization laser for REMPI, and the molecular mass as analytical parameters. In this work, a novel analytical scheme for detection of chlorinated aromatic compounds, including isomeric ensembles, by GC/REMPI-TOFMS is presented. The concept uses an in-line hydrodechlorination catalyst for post- or precolumn derivatization of chlorinated aromatic compounds. The chlorinated aromatics are quantitatively reduced, forming their respective aromatic skeletons. These aromatic skeletons are detected selectively by REMPI-TOFMS. The first results for substance class selective detection of chlorinated benzene isomers are given, and potential applications in the field of the analysis of compounds such as polychlorinated dibenzo-p-dioxins and -furans are discussed

The use of multi-channel silicone rubber traps as denuders for polycyclic aromatic hydrocarbons.

Atmospheric polycyclic aromatic hydrocarbons are ubiquitous environmental pollutants, which may be present both in the gaseous phase and adsorbed onto the surface of particles. Denuders are sampling devices which have been effectively employed in such partitioning applications. Here we describe and characterise a novel miniature denuder consisting of two multi-channel silicone rubber traps (each 178 mm long, 6 mm o.d. containing 22 silicone tubes), separated by a quartz fibre filter for particle phase collection. The denuder only requires a small portable personal sampling pump to provide sampling flow rates of similar to 0.5 L min(-1). Theoretical considerations indicated that the air flow through the denuder was expected to be laminar, and the linear velocity arising from longitudinal diffusion was found to be negligible. The calculated particle transmission efficiency through the denuder was found to be essentially 100% for particles > 50 nm, whilst the experimental overall efficiency, as determined by CPC and SMPS measurements, was 92 +/- 4%. The size resolved transmission efficiency was <60% for particles below 20 nm and 100% for particles larger than 200 nm. Losses could have been due to diffusion and electrostatic effects. Semi-volatile gaseous analytes are pre-concentrated in the silicone of the trap and may be thermally desorbed using a commercially available desorber, allowing for total transfer and detection of the collected analytes by GC-MS. This enhances detection limits and allows for lower sampling flow rates and shorter sampling times, which are advantageous for studies requiring high temporal resolution

Critical review of the analysis of brominated flame retardants and their environmental levels in Africa

World-wide, the prevalence of brominated flame retardants (BFRs) is well documented for routine analysis of environmental and biological matrices. There is, however, limited information on these compounds in the African environment and insufficient information on the analytical approaches used to obtain data. This paper presents a review on BFR levels in the African environment and the various analytical methodologies specifically applied in Africa for polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls and alternative-BFRs. The analyses include liquid sample preparation using liquid-liquid and solid phase extraction and solid sample preparation involving Soxhlet extraction, with ultrasound-assisted extraction increasingly being applied. Instrumental detection techniques were limited to gas chromatography coupled with electron capture detector and electron impact ionisation with single quadrupole mass spectrometers. Information on congener profile prevalence in indoor dust, soil, aquatic environment (water, sediment, and aquatic organisms), eggs, wastewater treatment plant compartments, landfills (leachate and sediment) and breast milk are presented. Although PBDEs were inconsistently detected, contamination was reported for all investigated matrices in the African environment. The manifestation in remote regions indicates the ubiquitous prevalence and long-range transport of these compounds. Levels in sediment, and breast milk from some African countries were higher than reported for Asia and Europe. Due to limited data or non-detection of alternative-BFRs, it is unclear whether banned formulations were replaced in Africa. Most of the data reported for BFR levels in Africa were obtained in non-African laboratories or in South Africa and formed the basis for our discussion of reported contamination levels and related methodologies

Investigating the trace polar species present in diesel using high-resolution mass spectrometry and selective ionization techniques.

The trace polar species present in diesel were investigated by combining selective ionization with high-resolution mass spectrometry. To eliminate matrix effects, the polar fraction was extracted using methanol and direct infusion with electrospray ionization and mass analysis were performed. The advantages and limitations of time-of-flight mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry for diesel analysis were discussed. Complementary information was obtained by considering both positive- and negative-ion mass spectra in terms of compounds that form part of the inherent fuel composition and compounds that represent fuel additives. In addition, diluted fuels were separated by gas chromatography prior to atmospheric pressure chemical ionization and mass analysis. Results showed that a large portion of unsaturated polycyclic hydrocarbons were not detected during direct infusion experiments, indicating that these species were not extracted efficiently with methanol and/or ionized efficiently with electrospray

Characterisation of particle collection and transmission in a polydimethylsiloxane based denuder sampler.

Denuder sampling devices consisting of two multi-channel silicone rubber traps separated by a quartz fibre filter, have been effectively employed for the simultaneous sampling of gas and particle associated semi-volatile organic compounds. Here controlled laboratory experiments were conducted to further elucidate the fundamental operating mechanisms of this portable denuder with respect to particle transmissions. Particle collection efficiency of the quartz fibre filters as well as particle transmission efficiency through the silicone rubber traps using ambient aerosol and aqueous suspensions of monodisperse polystyrene latex (PSL) as test particles (0.3, 0.5 and 0.8 mu m), were evaluated for various scenarios. Particle size and number concentration were measured with a scanning mobility particle sizer. Transmission efficiency of the denuder was determined from the ratio of particle concentration transmitted by the denuder to that of a bypass line. All sizes of PSL particles were collected with high efficiency and reproducibility by the quartz fibre filter ( > 98% with variation coefficients < 16%). Overall transmission efficiencies for all particles > 100 nm ranged from 91% to 100% (variation coefficients of 2-14%). Transmission efficiencies decreased when PDMS tubes were twisted but were not significantly different for traps made by different individuals. Ambient particles, which were studied for the first time, were collected with 88-95% collection efficiency. Losses of smaller particle size fractions in the trap portion of the denuder were likely due to diffusion and electrostatic effects. The high particle collection and transmission efficiencies of all tested particle sizes indicated that these denuders are very effective tools for aerosol measurements