WHAT’S NEW IN THE ANALYSIS OF COMPLEX ENVIRONMENTAL MATRICES?
Dr Leon Barron describes the analytical protocols he has developed to screen drugs in waste water
This was the question posed at a meeting held in the Royal Society of Chemistry (RSC) Burlington House headquarters in London in March. The one day conference was organised jointly by the Environmental Chemistry Group, the Water
Science Forum and the Separation Science Group of the RSC and covered a wide range of topics of interest to those interested in the application and practice of environmental analysis. This brief report highlights some of the interesting themes and the relevant topics presented by leading scientists in their fi eld.
Waste Water Analysis and Profi ling
Dr Leon Barron from Kings College London gave a very engaging presentation on the screening of complex forensic and environmental samples using high resolution analysis and in-silico data mining tools. He described the screening of waste water entering London’s sewage treatment works using liquid chromatography coupled with high resolution mass spectrometry (LC- HRMS) for pharmaceutical residues, drugs of abuse and compounds indicative of clandestine explosive manufacture. The use of HRMS produces large volumes of data rich in isotopic and structural information but analysis of the data can be diffi cult. Dr Barron and his co-workers have developed in-silico data mining, including retention time models using artifi cial neural networks (1) and machine learning, to facilitate the analysis of these large data sets. He also described the application of the techniques for the community-wide estimation of drug and pharmaceuticals consumption in England using wastewater analysis for a large number of compounds including stimulants, hallucinogens and their metabolites, opioids, morphine derivatives, benzodiazepines, and anti-depressants.
Dr Barron also described a very interesting application of SPE pre-concentration with LC-HRMS of a range of organic explosives in London’s waste water in an attempt to identify illicit explosive manufacturing activities.
Waste water analysis was also covered by Erika Castrignanò, from Professor Barbara Kasprzyk-Hordern’s Environmental Chemistry Group at the University of Bath UK, who described their work developing urban water analysis techniques for the profi ling of community wide health and lifestyle trends. Metabolites of compounds of interest which were present at detectable levels and had good stability were targeted, including specifi c biomarkers for cocaine use, and the results were used to generate the health and lifestyle profi les. The group also employed enantioselective analysis and ratio comparison to give valuable insights into legal and illicit drugs use e.g. by tracking the S+R isomeric ratio of amphetamine in waste water they could monitor the use of both prescribed and illicit drugs. The technique was also employed to monitor MDMA (ecstasy) in waste water as one isomer is metabolised and the other is not - thus determining the enantiomeric ratios allowed the researchers to track whether the drugs had resulted from human consumption or direct disposal into the waste water system. Many metabolites of interest are also enantiomeric and tracking their concentrations can therefore be employed to generate insight into community wide health and lifestyle trends.
Luigi Lopardo from the same group went on to describe the applications of these techniques to study community-wide exposure routes and risks from environmental endocrine disrupting chemicals.
Prof Jacob De Boer discusses the rise in brominated fl ame retardants in the marine environment
Pictures (Courtesy of Dr Roger Reeve, RSC Environmental Chemistry Group) Fire Retardants in the Environment
Both Prof Jacob De Boer (Vrije Universiteit Amsterdam, Netherlands) and Prof Stuart Harrad (University of Birmingham, UK) discussed the increasing concerns around the rising levels of fi re retardant chemicals in the environment and especially indoors in the home and workplace. Professor Harrad introduced brominated fi re retardants and described how they added to a wide range of products to make the them more fi re resistant by slowing the burning process. For example, in many plastic components, such as the carcasses of TVs, PCs, phones, games consoles and tablets, the levels can be as high as 30% and in furniture typically 2-3%, and this has resulted in high levels being detected in the household environment and therefore signifi cantly increasing human exposure to these chemicals. He described how the levels of PolyBrominated DiEthers (PBDE) detected in human milk has been doubling every 5 years and this together with increasing levels in household dust etc. has led to increasing concern for the effects of these chemicals on health. A major area of concern was the growing levels of electronic waste (circa 20m tonnes pa) containing high levels of these compounds and how it is processed and recycled. He described how levels of Hexabromocyclododecane in air at an e-waste centre was 400 times higher than the background.
In the developed countries increasing awareness of the issues was being addressed by legislation but in developing countries e-waste control was not widespread and this was a major problem for exposed workers, the food chain and the wider environment. He described his work studying levels found in animals from the food chain near e-waste sites in China (2). High-end estimates of exposure for young children eating these foods exceeded the U.S. Environmental Protection Agency reference doses for BDE-47 and BDE-99 by factors of approximately 2.5 and 1.5, respectively.
Although e-waste is now largely separated from waste before landfi ll there is still a legacy issue and Prof Harrad described the development of leaching experiments under landfi ll conditions where they observed high leachate concentrations especially from textile based wastes. TCPP (tris (1-chloro-2-propyl) phosphate) is a fl ame retardant, commonly used in polyurethane foam in consumer products and home insulation, and in experiments which mimicked rainfall leaching cycles the team found that almost all (96%) had been leached after only 6 cycles thus raising concerns for possible contamination of the water table.
Another area of concern was that they are now fi nding increasing levels of fl ame retardants in items which do not need fi re retardancy, for example in cooking utensils with black plastic components, due to the increasing use of recycled plastics
Prof Jacob De Boer in his Keynote lecture described the application of Direct Probe - ACPI(+)-TOF-MS to screen for brominated fl ame retardants (BFR) present at high levels in a range of sample matrices. Using this technique, a sample can be screened every 2 minutes for a selected target compounds. A comparison of BFRs found in sewage sludge in the UK and the Netherlands showed
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