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The global decline of seagrass meadows due to sustained pressure from anthropogenic activities and the ongoing threat from climate change has weakened their capacity for supporting coastal productivity and fisheries habitats, while also increasing sediment erosion. The ongoing efforts to prevent seagrass decline require novel tools to monitor seagrass health and assess the effects of habitat management. Such monitoring tools require the use of sensitive indicators to assess the intensity of environmental stressors and to monitor the corresponding responses of seagrass. Environmental metabolomics has proven valuable in identifying such phenotypic traits of abiotic and biotic stress in plants. The identification of metabolite changes in seagrass linked to an environmental stress response may lead to the development of a molecular diagnostic tool that could be used to give an early warning of seagrass stress. Therefore, we explore the potential of one- and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (1D and 2D GC-TOFMS) in Australia’s most threatened seagrass species—Zostera muelleri. Overall, GC×GC-TOFMS outperformed GC-TOFMS and offered a robust, comprehensive, and superior analytical sensitivity and resolution with a total of 156 metabolites compared to 93 identified in GC-TOFMS. Among these metabolites, > 50% were identified exclusively in GC×GC-TOFMS and include secondary metabolites of the phenylpropenoid class, phytohormones, and various sugar and amino acid derivatives. Therefore, GC×GC-TOFMS represents a comprehensive metabolomics platform for both discovery and targeted studies in seagrass that may aid diagnostic tool development for more targeted seagrass management.

The coupling of comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry offers the best separation efficiency combined with accurate mass measurements over a wide mass range. The tremendous power of this screening tool is illustrated by trace qualitative screening analysis of organohalogenated compounds (OHCs) in pet cat hair. Tentative identification was supported by mass spectral database searches and elemental formula prediction from the experimentally determined accurate mass data. This screening approach resulted in the first tentative identification of pentabromoethylbenzene, decabromodiphenyl ethane, hexabromocyclododecane, trisbromoneopentyl alcohol, tris(2-chloroethyl) phosphate and tris(2-chloroisopropyl)phosphate in the South African indoor environment. A total of seventy-two OHCs were identified in the samples and include known flame retardants, such as polybrominated diphenyl ethers, and legacy contaminants such as polychlorinated biphenyls and organochlorine, organophosphorous and pyrethroid pesticides. The results obtained from cat hair indicate that these pets are exposed to complex mixtures of OHCs and the detection of these compounds suggests that non-invasive cat hair samples can be used to model indoor exposure with reference to external deposition of OHCs present in the air and dust surrounding people. Toddlers share the same environment as pet cats and therefore also the same health risks.

We outline the experiences and the challenges of optimizing two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOF-MS) in conjunction with the H4IIE-luc bio-assay for analyzing polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the South African context. Investigating such alternative analytical methods can assist countries with developing economies to meet their obligations under the Stockholm Convention.

Comprehensive Gas Chromatography-Time-of-Flight Mass Spectrometry (GC×GC-TOFMS) methodology has been refined for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in samples with different matrices. This is specifically for application in developing countries where access to gas chromatography-high resolution mass spectrometry (GC-HRMS) and highly skilled personnel is limited. The method, using an Rxi-5 Sil MS column in the first dimension ((1)D) coupled with an Rtx-200 column in the second dimension ((2)D), was used to quantify PCDDs and PCDFs in different environmental sample matrices. The results were compared with those obtained using GC-HRMS and good agreement was observed. The limit of detection (LOD) for the method (300fg on column for spiked soil samples) was determined using an Rxi-XLB ((1)D) column coupled with an Rtx-200 column ((2)D). Preliminary South African sample results are also discussed. Isomer specificity for different tetrachloro dibenzo-p-dioxins (TCDDs) and tetrachloro dibenzofurans (TCDFs) was investigated using a commercial standard. Adequate resolution was achieved. The method as described has great attraction for developing countries being both financially and operationally favourable.

The disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC×GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non-ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC×GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC×GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination.

Water pollution events may arise rapidly, requiring a methodology that is easy to implement, fast to deploy, and sufficiently sensitive to detect the trace presence of hazardous contaminants. A cheap and easy to use silicone rubber (polydimethylsiloxane (PDMS)) miniature passive sampler is described. In order to test the methodology, pollutants were concentrated, in situ, from surface water in and around Pretoria, South Africa. The versatile sampler allowed for conventional and enhanced sensitivity, solvent-free analysis by comprehensive gas chromatography – time of flight mass spectrometry (GCxGC-TOFMS) and high resolution TOFMS (GC-HRT). Contaminants detected in surface water include caffeine, personal care products, pharmaceuticals, pesticides and polycyclic aromatic hydrocarbons.Keywords: passive sampler, silicone rubber (PDMS) tubing, GCxGC-TOFMS, GC-HRT, surface water quality