Water / Wastewater
chloride salt and sodium citrate buffers). We have modified the QuEChERS protocol for the extraction of a suite of pharmaceuticals and biocides by adopting ingredients of the different methods, i.e., using 4 g of magnesium sulphate and 1.5 g of sodium acetate. To assess the extraction performance, the matrix effects (%ME) and recovery (%REC) of each compound was investigated in water and soil samples fortified with a mixture of pharmaceuticals and biocides. These were prepared as three sets of quality control samples (QCs) containing known amounts of analyte using a ‘spike before’ and ‘spike after’ extraction approach for recovery, along with a non-extracted QC to measure matrix effects [11]. For an ideal preparative method we would look to achieve the following: 1) repeatable data (%ME and %REC), 2) low matrix effects (~100%) and, 3) high analyte recoveries. To understand the potential for reducing costs further and offering better alignment with the needs of clinical samples, we have also undertaken a ‘proof-of- concept’ study using lower sample volumes and extraction materials as ‘miniaturised’ mini-QuEChERS method.
Figure 2: A selection of bar charts (A-C) describing the extraction performance of the QuEChERS method for a water sample containing a selection of pharmaceuticals and biocides with a reduction in operating scale of the extraction (sample volume and extraction materials) from 4:1:0.5. Error bars shown represent the standard error observed for the matrix effects and recovery.
Results
Figure 3: A bar chart illustrating the extraction performance of the QuEChERS method for a spiked soil sample with the selection of pharmaceuticals and biocides. Error bars shown represent the standard error observed for the matrix effects and recovery.
cost, estimated at 63% for the extraction cartridges alone. It is therefore, prudent to investigate the potential of the QuEChERS method further as an example of a translational approach of sample preparation.
The method consists of a two-step extraction; 1) a liquid partition into acetonitrile with the addition of drying agents, salts and buffers to limit polar interferences and facilitate phase transfer respectively, followed by, 2) a dispersive solid-phase extraction (dSPE) for further interference removal (see figure 1). There are two buffered methods, that recognised by AOAC (using sodium acetate salt) and the EN method (a combination of sodium
Author Contact Details A. R. Godfrey*1
, D. Pignetti1 , M. Smith1 , C. Desbrow2
The QuEChERS extraction has shown considerable flexibility for method development and application with efficacy for different chemical substances and sample matrices. This is evidenced in example (pilot) data (figure 2) illustrating the extraction of common pharmaceuticals and biocides of variable lipophilicity/ acidity, using higher sample volumes of 4 mL typical of environmental matrices. The analytes were extracted with reasonable precision (relative standard deviation (RSD) of <20% for most pharmaceuticals and biocides tested) and a median recovery value of 48.9% for the suite. Importantly, there appears
to be reasonable control of matrix effects for these compounds (values ~100%, with precision of <20%RSD) enabling a more meaningful recovery measure to be drawn from the extraction. Interestingly, when the scale of the extraction is reduced in terms of sample volume and extraction material the data appears to show an optimum operating condition. For data acquired with a 1 mL sample volume (see figure 2) each metric of performance typically improved for all compounds studied showing precision <20%RSD, minimal matrix effects (median 103.9%), and improved recovery (median 53.2%)). This is pleasing, providing evidence that this approach has the potential for application in
27
other areas of science where considerably less sample volume is available (e.g. clinical) unlike that conventionally associated with environmental samples. The method has also shown significant promise in extracting certain environmental samples; QuEChERS has shown similar repeatability of performance in soil (relative standard deviation (RSD) of <20% for the majority of pharmaceuticals and biocides) with a median recovery value of 56.4% for the suite (see figure 3). This provides promise of a workable method in monitoring receiving land for chemical contamination following wastewater sludge deposition.
Conclusion
This sample preparation method has shown efficacy in extracting different chemistries with data presented here concerning a small selection of pharmaceuticals (of environmental interest) and surfactant biocides. Using higher sample volumes (4 mL) most compounds (7/9) showed good precision (RSD<20%), matrix effects (median 103.4%), and recovery (median 48.9%). Regarding use, this offers a labour-saving and cost effective, approach for high throughput analysis versus current protocols. We currently estimate that extraction costs can be reduced by >60% solely from the extraction cartridges and further still with analyst time saved (hours to ~20 minutes per sample). We have also shown the potential for a mini-QuEChERS approach, offering improved extraction performance for all compounds studied (precision <20%RSD, matrix effects (median 103.9%), and recovery (median 53.2%)) and additional potential savings in production and customer purchase costs. This, with the flexibility and translational nature of the technique, offers significant benefits for environmental analysis and an interesting sample preparation prospect for other matrices such as those encountered in clinical work.
References
1. Oxford English Dictionary. 3rd ed. Oxford: Oxford University Press; 2000 [cited 23 August 2018]. Available from: https://
en.oxforddictionaries.com/definition/pollution
2. Department for Environment Food and Rural Affair (DEFRA). Waste water treatment in the United Kingdom – 2012. DEFRA. 2012. Report No.: PB13811.
3. Prakash V, Bishwakarma MC, Chaudhary A, Cuthbert R, Dave R, Kulkarni M, Kumar S, Paudel K, Ranade S, Shringarpure R, Green RE. The population decline of Gyps Vultures in India and Nepal has slowed since veterinary use of diclofenac was banned. PLoS ONE. 2012; 7(11): e49118.
4. Galligan TH, Amano T, Prakash VM, Kulkarni M, Shringarpure R, Prakash N, Ranade S, Green RE, Cuthbert RJ. Have population declines in Egyptian Vulture and Red-headed Vulture in India slowed since the 2006 ban on veterinary diclofenac? Bird Conservation International. 2014: 1-10.
5. Kidd KA, Blanchfield PJ, Mills KH, Palace VP, Evans RE, Lazorchak JM, Flick RW. Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences (PNAS). 2007; 104 (21): 8897-8901.
6. Anderson SE, Meade BJ. Potential Health Effects Associated with Dermal Exposure to Occupational Chemicals. Environmental Health Insights. 2014; 8 (Suppl. 1): 51–62.
7. Hahn S, Schneider K, Gartiser S, Heger W, Mangelsdorf I. Consumer exposure to biocides - identification of relevant sources and evaluation of possible health effect. Environmental Health, 2010; 9:7.
8. Schweer C. Biocides – risks and alternatives. Challenges and perspectives regarding the handling of biocides in the EU. PAN Germany. 2010.
9.
https://www.ukwir.org/the-chemicals-investigation- programme-phase-2,-2015-2020
10.Anastassiades, M., Lehotay, S. J., Štajnbaher, D., & Schenck, F. J. (2003). Fast and easy multiresidue method employing acetonitrile extraction/partitioning and “dispersive solid-phase extraction” for the determination of pesticide residues in produce. Journal of AOAC international, 86(2), 412-431.
11.Matuszewski BK, Constanzer ML, Chavez-Eng CM. Strategies for the assessment of matrix effect in quantitative bioanalytical methods based on HPLC - MS/MS. Analytical Chemistry. 2003; 75 (13): 3019-3030.
, R. Townsend1
1Institute of Mass Spectrometry, School of Medicine • Swansea University, UK, SA2 8PP 2
Biotage GB Ltd • Ystrad Mynach, Hengoed, UK, CF82 7TS *Corresponding author at: • Tel.: +44 1792 295915 • Email:
a.r.godfrey@swansea.ac.uk
www.envirotech-online.com IET November / December 2018
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