Systematic assessment and profiling of volatile organic chemicals in commercial shipping containers based on new material physical sorption sampling technology

Nik Radevski

Globalization of trade has led to a worldwide dramatic increase in the use of shipping containers. More than two and half million international shipping containers are involved in the daily transport of cargo. During holding and transportation, toxic and hazardous gases called volatile organic chemicals (VOCs) are released from the transported cargo and packaging materials, within the sealed containers. Particularly, the containers may carry fumigant residues associated with quarantine or phytosanitary required disinfestations of pests. The inter-reaction of those compounds can form even more toxic and dangerous substances. Therefore, worldwide concerns have been raised due to VOCs in shipping containers as they have threatened the health of workers and challenged environmental safety. Ethyl formate has been introduced as a new fumigant for shipping container fumigation. However, the stability and inter-reactions of ethyl formate with other VOCs in shipping containers are unknown. Therefore, the research strategy of this PhD project has been designed firstly to develop a novel method and protocol for collection and extraction of VOCs, and to build a chemical finger-print database; secondly conduct systematic laboratory evaluation on the stability and inter-reactions of ethyl formate with ten reported common VOCs in containers; finally, validate the novel method and the laboratory database to explore the changes of VOCs in commercial shipping containers loaded with different cargos with and without ethyl formate fumigation. In the laboratory, ethyl formate fumigant was stable under 60°C with three different humidities (0%, 30% and 60%) and had no inter-reactions between fumigant residues and the ten VOCs. To validate the laboratory results, fieldwork was conducted to systematically characterize VOC profiles and fumigant residues. The novel in-situ sampling method was developed with headspace solid phase microextraction (HS-SPME). The technology was functionally highly sensitive and provided solvent-free enrichment. The polymer-like film coatings and synthetic porous solid particle coatings were based on an inert large Brunauer-Emmett-Teller (BET) surface physical sorption and occurred without chemical inter-reaction between VOCs and the coated material. The approach monitored eighty-one shipping containers. SPME collected and extracted VOCs for gas chromatography-mass spectrometry (GC-MS), equipped in a mobile-laboratory, for onsite analysis. Fifty-five VOCs were found and identified from four categories of cargo sources, machinery and parts, woods and packaging, dangerous goods, and dry foods. Ethyl formate, ethylbenzene, styrene, naphthalene, and xylenes are common compounds that were identified and detected across the four categories during the commercial field trials. This project is the first to report and provide a data package from the laboratory-based systematic study on the stability and inter-reactions of ethyl formate with known VOCs. It includes the development of a chemical fingerprint database and employs a mobile-laboratory for onsite VOC monitoring to validate novel methods and protocols for the collection and extraction of VOCs from a large number of commercial containers. These research outputs and outcomes will contribute to generating occupational and environmental health and safety policies and regulations.

Systematic assessment and profiling of volatile organic chemicals in commercial shipping containers based on new material physical sorption sampling technology

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