QuEChERS – AN ALTERNATIVE APPROACH TO MONITORING ENVIRONMENTAL POLLUTION?
What is pollution?
The Oxford English Dictionary states that this is ‘the introduction of harmful substances or products into the
environment’ [1]. This description automatically conjures images of the Exon Valdez oil spill or big fume clouds over a city. However, a pollutant can be something as small and insignifi cant as a common pharmaceutical, or even the active component within a household cleaning product. Just take a moment to think about the pharmaceuticals you have in your cupboards at home; paracetamol, ibuprofen, aspirin or maybe hay fever medicines such as loratadine or cetirizine. What about cleaning or personal care products? Have you ever thought about what happens to these products once they’ve been used?
Like any foodstuff, once a drug has been taken it is excreted from the body into the wastewater system with other household waste. While it was initially thought that small molecules, like pharmaceuticals, are degraded during wastewater treatment, research has shown this isn’t the case. So why is this such a problem? Similarly to domestic recycling that we are all required to undertake, waste is often more manageable when separated. Wastewater is no different and is segregated as solid and liquid fractions following (or as part of) treatment; water is then released into water courses with the majority (80%) of treated solids (sludge) recycled back onto agricultural land as fertiliser [2] and the remainder often placed in landfi ll. Given this recycling process, there is a potential for pollutants present within these wastewater fractions to bioaccumulate and enter the food chain through agricultural and fi shery stock. It is therefore key that we do not underestimate the impact of our waste on environmental and public health. Already there have been global reports of the adverse effects of pharmaceuticals on the animal kingdom. For
example, the non-steroidal anti-infl ammatory, diclofenac, has caused multiple species of vulture in Asia to become critically endangered [3] with the Indian long-billed vulture and red-headed vulture populations showing a decrease of 97-99% [4]. The female contraceptive pill is another with longstanding environmental impact, feminising male fi sh causing a rapid decrease in population over a 2 year monitoring period [5]. Due to the demands for environmental monitoring programmes, more candidate pollutants are being discovered in recycled waste with a signifi cant potential impact for both environmental and public health. For example, biocides have been linked to a number of ailments, from skin irritation to breathing disorders [6,7], and the use of tributyltin (TBT), an antifouling agent, has been shown to have a long-lasting impact on marine eco-systems [8]. This information alone begs the questions ‘if’ and ‘at what point’ our behaviour will have an impact on human health if nothing changes?
Regulation
The introduction of the Water Framework Directive (2000/60/ EC)) in 2000 was a ‘game-changer’ for environmental monitoring. Member states were now obligated to look at the environment with a more holistic approach, considering the impact of environmental pollution on the ecosystem as a whole. This included water courses but also land and organisms living in these catchments such as biota. Information gathered from monitoring programmes following the introduction of this policy led to the development of environmental standards for hazardous substances, the environmental quality standards directive (EQSD) (2008/105/ EC). The Chemical Investigation Programme (CIP), established in 2009, was a UK based initiative aimed at developing these directives to identify and understand the prevalence of potential pollutants within wastewater samples to set quality standards in wastewater. The initial CIP study highlighted substances, including a selection of pharmaceuticals, of emerging concern to environmental pollution that are not yet subject to legislation but specifi ed on a “watch list”. These substances include three pharmaceuticals and are subject to a monitoring programme, gathering data to determine the risk within the environment. In 2015, CIP II was launched to investigate these pharmaceuticals and a broader scope of compounds of potential environmental concern, focusing on their levels in environmental samples to inform policy [9].
The sample preparation problem
To determine the extent of pharmaceutical pollution the content within environmental sample matrices fi rst needs to be established using a suitable sample preparation method. Similarly to the principles of waste recycling, a key objective of sample preparation for trace analysis will be separation – enabling the detection of trace materials (albeit with potentially higher potency) than more abundant materials. Current recognised methods for preparing complex environmental matrices such as soil and wastewater effl uent for analysis are typically multi-step procedures using a range of techniques and apparatus, resulting in methods that are time and resource consuming, unsuitable for high-throughput analysis. Our work has investigated a new approach to preparing samples for monitoring levels of commonly used pharmaceuticals in environmental samples, as detailed by UK Water Industry Research and the Chemical Investigation Programme. These have been included along with other chemicals (biocides) commonly used in a domestic capacity that may contribute to pollution levels in wastewater. The Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) protocol is a sample preparation method developed by Michelangelo Anastassiades and Steven Lehotay for the extraction of pesticides from fruits and vegetables [10]. Compared to recognised environmental preparative methods for wastewater and solid samples, this approach potentially offers a reduction in: 1) preparation time, from hours to ~20 minutes per sample and, 2)
Figure 1: Generic protocol for the QuEChERS extraction detailing the two stage process of partition using the initial extraction kit, and dispersive solid phase extraction (dSPE).
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