Publications
89 results found
McEneff GL, Richardson A, Webb T, et al., 2018, Sorbent film-coated passive samplers for explosives vapour detection Part B, Deployment in Semi-Operational Environments and Alternative Applications, Vol: 8, Pages: 1-13, ISSN: 2045-2322
The application of new sorbent-film coated passive samplers for capture of bulk commercial and military explosives vapours in operationally relevant spaces such as luggage, rooms, vehicles and shipping containers is presented. Samplers were easily integrated with in-service detection technologies with little/no sample preparation required. Ethylene glycol dinitrate (EGDN) was detected within 4 h in a container holding a suitcase packed with 0.2 kg Perunit 28E. Within a 22,000 dm3 room, 1 kg of concealed Seguridad was detected within 24 h and in an adjoining room within 7 days. Exposed samplers also successfully captured components of 1 kg TNT after 72 h and 1 kg concealed Perunit 28E after 6 h in both a furnished room and a large, partially filled shipping container. For the latter, samplers captured detectable residues outside the container after 24 h and were stable during wet weather for 72 h. A one-week trial at three operationally relevant venues including a university, a theatre and a government building revealed a nuisance positive rate of <1.4% (n = 72). Finally, two alternative applications are presented for extraction of liquid samples and use a particulate contact swab showing flexibility for a range of different search activities.
McEneff GL, Murphy B, Webb T, et al., 2018, Sorbent film-coated passive samplers for explosives vapour detection Part A, Materials Optimisation and Integration with Analytical Technologies, Vol: 8, Pages: 1-13, ISSN: 2045-2322
A new thin-film passive sampler is presented as a low resource dependent and discrete continuous monitoring solution for explosives-related vapours. Using 15 mid-high vapour pressure explosives-related compounds as probes, combinations of four thermally stable substrates and six film-based sorbents were evaluated. Meta-aramid and phenylene oxide-based materials showed the best recoveries from small voids (~70%). Analysis was performed using liquid chromatography-high resolution accurate mass spectrometry which also enabled tentative identification of new targets from the acquired data. Preliminary uptake kinetics experiments revealed plateau concentrations on the device were reached between 3–5 days. Compounds used in improvised explosive devices, such as triacetone triperoxide, were detected within 1 hour and were stably retained by the sampler for up to 7 days. Sampler performance was consistent for 22 months after manufacture. Lastly, its direct integration with currently in-service explosives screening equipment including ion mobility spectrometry and thermal desorption mass spectrometry is presented. Following exposure to several open environments and targeted interferences, sampler performance was subsequently assessed and potential interferences identified. High-security building and area monitoring for concealed explosives using such cost-effective and discrete passive samplers can add extra assurance to search routines while minimising any additional burden on personnel or everyday site operation.
Gallidabino MD, Hamdan L, Murphy B, et al., 2018, Suspect screening of halogenated carboxylic acids in drinking water using ion exchange chromatography – high resolution (Orbitrap) mass spectrometry (IC-HRMS), TALANTA, Vol: 178, Pages: 57-68, ISSN: 0039-9140
Retrospective in silico screening of analytical data for the identification of new or emerging disinfection by-products in drinking waters could be useful to assess quality and potential hazards, as well as help implement mitigation procedures more rapidly. Herein, the first study coupling ion exchange chromatography (IC) with high resolution mass spectrometry (HRMS) for the determination of halogenated carboxylic acid disinfectant by-products is reported. Separation was achieved using a Metrohm A Supp 5 column and a Na2CO3/NaHCO3 gradient eluent from 1/0.31 to 10/3.1 mM. A variety of solid phase extraction (SPE) sorbents were tested for added selectivity to organic ions and Isolute ENV+ cartridges were selected because of their best overall extraction performance. Method LODs were in the μg L−1 concentration range, with R2 ≥ 0.99 for all the analytes, and isobaric ions could be easily discriminated using HRMS. The method was applied to municipal drinking water. Targeted quantitative analysis revealed the presence of 10 haloacetic acids at levels not exceeding the limits set by WHO and USEPA. Furthermore, suspect screening for additional halogenated carboxylic acids via retrospective HRMS data analysis also indicated the presence of other iodinated HAAs and chlorinated propionic acids, of which one (i.e. monochloropropionic acid) is discussed here for the first time. Most importantly, several potential suspects could be eliminated from further consideration through HRMS data analysis alone. To our knowledge, this represents the first time that a retrospective IC-HRMS screen of halogenated carboxylic acids in drinking water has been reported.
Mollerup CB, Mardal M, Dalsgaard PW, et al., 2018, Prediction of Collision Cross Section and Retention Time for Broad Scope Screening in Gradient Reversed-Phase Liquid Chromatography-Ion Mobility-High Resolution Accurate Mass Spectrometry, Journal of Chromatography A, ISSN: 0021-9673
Exact mass, retention time (RT), and collision cross section (CCS) are used as identification parameters in liquid chromatography coupled to ion mobility high resolution accurate mass spectrometry (LC-IM-HRMS). Targeted screening analyses are now more flexible and can be expanded for suspect and non-targeted screening. These allow for tentative identification of new compounds, and in-silico predicted reference values are used for improving confidence and filtering false-positive identifications. In this work, predictions of both RT and CCS values are performed with machine learning using artificial neural networks (ANNs). Prediction was based on molecular descriptors, 827 RTs, and 357 CCS values from pharmaceuticals, drugs of abuse, and their metabolites. ANN models for the prediction of RT or CCS separately were examined, and the potential to predict both from a single model was investigated for the first time. The optimized combined RT-CCS model was a four-layered multi-layer perceptron ANN, and the 95th prediction error percentiles were within 2 minutes RT error and 5% relative CCS error for the external validation set (n = 36) and the full RT-CCS dataset (n = 357). 88.6% (n = 733) of predicted RTs were within 2 minutes error for the full dataset. Overall, when using 2 minutes RT error and 5% relative CCS error, 91.9% (n = 328) of compounds were retained, while 99.4% (n = 355) were retained when using at least one of these thresholds. This combined prediction approach can therefore be useful for rapid suspect/non-targeted screening involving HRMS, and will support current workflows.
Miller TH, Bury NR, Owen SF, et al., 2017, Uptake, biotransformation and elimination of selected pharmaceuticals in a freshwater invertebrate measured using liquid chromatography tandem mass spectrometry, Chemosphere, Vol: 183, Pages: 389-400, ISSN: 0045-6535
Methods were developed to assess uptake and elimination kinetics in Gammarus pulex of nine pharmaceuticals (sulfamethazine, carbamazepine, diazepam, temazepam, trimethoprim, warfarin, metoprolol, nifedipine and propranolol) using targeted LC-MS/MS to determine bioconcentration factors (BCFs) using a 96 h toxicokinetic exposure and depuration period. The derived BCFs for these pharmaceuticals did not trigger any regulatory thresholds and ranged from 0-73 L kg−1 (sulfamethazine showed no bioconcentration). Metabolism of chemicals can affect accurate BCF determination through parameterisation of the kinetic models. The added selectivity of LC-MS/MS allowed us to develop confirmatory methods to monitor the biotransformation of propranolol, carbamazepine and diazepam in G. pulex. Varying concentrations of the biotransformed products; 4-hydroxypropranolol sulphate, carbamazepine-10,11-epoxide, nordiazepam, oxazepam and temazepam were measured following exposure of the precursor compounds. For diazepam, the biotransformation product nordiazepam was present at higher concentrations than the parent compound at 94 ng g−1 dw. Overall, the results indicate that pharmaceutical accumulation is low in these freshwater amphipods, which can potentially be explained by the rapid biotransformation and excretion.
Rapp-Wright H, McEneff G, Murphy B, et al., 2017, Suspect screening and quantification of trace organic explosives in wastewater using solid phase extraction and liquid chromatography-high resolution accurate mass spectrometry, Journal of Hazardous Materials, Vol: 329, Pages: 11-21, ISSN: 0304-3894
The first comprehensive assessment of 34 solid phase extraction sorbents is presented for organic explosive residues in wastewater prior to analysis with liquid chromatography-high resolution accurate mass spectrometry (LC-HRMS). A total of 18 explosives were selected including nitramines, nitrate esters, nitroaromatics and organic peroxides. Three polymeric divinylbenzene-based sorbents were found to be most suitable and one co-polymerised with n-vinyl pyrrolidone offered satisfactory recoveries for 14 compounds in fortified wastewater (77–124%). Limits of detection in matrix ranged from 0.026–23 μg L−1 with R2 ≥ 0.98 for most compounds. The method was applied to eight 24-h composite wastewater samples from a London wastewater works and one compound, 2,4-dinitrotoluene, was determined over five days between 332 and 468 g day−1 (225–303 ng L−1). To further exploit the suspect screening capability, 17 additional explosives, precursors and transformation products were screened in spiked wastewater samples. Of these, 14 were detected with recoveries from 62 to 92%, highlighting the broad applicability of the method. To our knowledge, this represents the first screen of explosives-related compounds in wastewater from a major European city. This method also allows post-analysis detection of new or emerging compounds using full-scan HRMS datasets to potentially identify and locate illegal manufacture of explosives via wastewater analysis.
Vidaki A, Ballard D, Aliferi A, et al., 2017, DNA methylation-based forensic age prediction using artificial neural networks and next generation sequencing, Forensic Science International-Genetics, Pages: 225-236, ISSN: 1872-4973
The ability to estimate the age of the donor from recovered biological material at a crime scene can be of substantial value in forensic investigations. Aging can be complex and is associated with various molecular modifications in cells that accumulate over a person's lifetime including epigenetic patterns. The aim of this study was to use age-specific DNA methylation patterns to generate an accurate model for the prediction of chronological age using data from whole blood. In total, 45 age-associated CpG sites were selected based on their reported age coefficients in a previous extensive study and investigated using publicly available methylation data obtained from 1156 whole blood samples (aged 2-90 years) analysed with Illumina's genome-wide methylation platforms (27K/450K). Applying stepwise regression for variable selection, 23 of these CpG sites were identified that could significantly contribute to age prediction modelling and multiple regression analysis carried out with these markers provided an accurate prediction of age (R2 =0.92, mean absolute error (MAE)=4.6 years). However, applying machine learning, and more specifically a generalised regression neural network model, the age prediction significantly improved (R2 =0.96) with a MAE=3.3 years for the training set and 4.4 years for a blind test set of 231 cases. The machine learning approach used 16 CpG sites, located in 16 different genomic regions, with the top 3 predictors of age belonged to the genes NHLRC1, SCGN and CSNK1D. The proposed model was further tested using independent cohorts of 53 monozygotic twins (MAE=7.1 years) and a cohort of 1011 disease state individuals (MAE=7.2 years). Furthermore, we highlighted the age markers' potential applicability in samples other than blood by predicting age with similar accuracy in 265 saliva samples (R2 =0.96) with a MAE=3.2 years (training set) and 4.0 years (blind test). In an attempt to create a sensitive and accurate age prediction test, a next gener
Zapata F, de la Ossa MªÁF, Gilchrist E, et al., 2016, Progressing the analysis of Improvised Explosive Devices, Comparative study for trace detection of explosive residues in handprints by Raman spectroscopy and liquid chromatography, Vol: 161, Pages: 219-227, ISSN: 0039-9140
Concerning the dreadful global threat of terrorist attacks, the detection of explosive residues in biological traces and marks is a current need in both forensics and homeland security. This study examines the potential of Raman microscopy in comparison to liquid chromatography (ion chromatography (IC) and reversed-phase high performance liquid chromatography (RP-HPLC)) to detect, identify and quantify residues in human handmarks of explosives and energetic salts commonly used to manufacture Improvised Explosive Devices (IEDs) including dynamite, ammonium nitrate, single- and double-smokeless gunpowders and black powder. Dynamite, ammonium nitrate and black powder were detected through the identification of the energetic salts by Raman spectroscopy, their respective anions by IC, and organic components by RP-HPLC. Smokeless gunpowders were not detected, either by Raman spectroscopy or the two liquid chromatography techniques. Several aspects of handprint collection, sample treatment and a critical comparison of the identification of compounds by both techniques are discussed. Raman microscopy and liquid chromatography were shown to be complementary to one another offering more comprehensive information for trace explosives analysis.
Ryu Y, Barceló D, Barron LP, et al., 2016, Comparative measurement and quantitative risk assessment of alcohol consumption through wastewater-based epidemiology: an international study in 20 cities, Science of the Total Environment, Vol: 565, Pages: 977-983, ISSN: 0048-9697
Quantitative measurement of drug consumption biomarkers in wastewater can provide objective information on community drug use patterns and trends. This study presents the measurement of alcohol consumption in 20 cities across 11 countries through the use of wastewater-based epidemiology (WBE), and reports the application of these data for the risk assessment of alcohol on a population scale using the margin of exposure (MOE) approach. Raw 24-h composite wastewater samples were collected over a one-week period from 20 cities following a common protocol. For each sample a specific and stable alcohol consumption biomarker, ethyl sulfate (EtS) was determined by liquid chromatography coupled to tandem mass spectrometry. The EtS concentrations were used for estimation of per capita alcohol consumption in each city, which was further compared with international reports and applied for risk assessment by MOE. The average per capita consumption in 20 cities ranged between 6.4 and 44.3 L/day/1000 inhabitants. An increase in alcohol consumption during the weekend occurred in all cities, however the level of this increase was found to differ. In contrast to conventional data (sales statistics and interviews), WBE revealed geographical differences in the level and pattern of actual alcohol consumption at an inter-city level. All the sampled cities were in the “high risk” category (MOE
Miller TH, Baz-Lomba JA, Harman C, et al., 2016, The first attempt at non-linear in silico prediction of sampling rates for polar organic chemical integrative samplers (POCIS), Environmental science & technology, Vol: 50, Pages: 7973-7981, ISSN: 0013-936X
Modeling and prediction of polar organic chemical integrative sampler (POCIS) sampling rates (Rs) for 73 compounds using artificial neural networks (ANNs) is presented for the first time. Two models were constructed: the first was developed ab initio using a genetic algorithm (GSD-model) to shortlist 24 descriptors covering constitutional, topological, geometrical and physicochemical properties and the second model was adapted for Rs prediction from a previous chromatographic retention model (RTD-model). Mechanistic evaluation of descriptors showed that models did not require comprehensive a priori information to predict Rs. Average predicted errors for the verification and blind test sets were 0.03 ± 0.02 L d-1 (RTD-model) and 0.03 ± 0.03 L d-1 (GSD-model) relative to experimentally determined Rs. Prediction variability in replicated models was the same or less than for measured Rs. Networks were externally validated using a measured Rs data set of six benzodiazepines. The RTD-model performed best in comparison to the GSD-model for these compounds (average absolute errors of 0.0145 ± 0.008 L d-1 and 0.0437 ± 0.02 L d-1, respectively). Improvements to generalizability of modeling approaches will be reliant on the need for standardized guidelines for Rs measurement. The use of in silico tools for Rs determination represents a more economical approach than laboratory calibrations.
Weston-Ford KA, Moseley ML, Hall LJ, et al., 2016, The retrieval of fingerprint friction ridge detail from elephant ivory using reduced-scale magnetic and non-magnetic powdering materials, Science and Justice, Vol: 56, Pages: 1-8, ISSN: 1355-0306
An evaluation of reduced-size particle powdering methods for the recovery of usable fingermark ridge detail from elephant ivory is presented herein for the first time as a practical and cost-effective tool in forensic analysis. Of two reduced-size powder material types tested, powders with particle sizes ≤ 40 μm offered better chances of recovering ridge detail from unpolished ivory in comparison to a conventional powder material. The quality of developed ridge detail of these powders was also assessed for comparison and automated search suitability. Powder materials and the enhanced ridge detail on ivory were analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy and interactions between their constituents and the ivory discussed. The effect of ageing on the quality of ridge detail recovered showed that the best quality was obtained within 1 week. However, some ridge detail could still be developed up to 28 days after deposition. Cyanoacrylate and fluorescently-labelled cyanoacrylate fuming of ridge detail on ivory was explored and was less effective than reduced-scale powdering in general. This research contributes to the understanding and potential application of smaller scale powdering materials for the development of ridge detail on hard, semi-porous biological material typically seized in wildlife-related crimes.
Gómez-Canela C, Miller T, Bury NR, et al., 2016, Targeted metabolomics of Gammarus pulex following controlled exposures to selected pharmaceuticals in water, Science of the Total Environment, Vol: 562, Pages: 777-788, ISSN: 0048-9697
The effects of pharmaceuticals and personal care products on aquatic organisms represent a significant current concern. Herein, a targeted metabolomics approach using liquid chromatography-high resolution mass spectrometry (LC-HRMS) is presented to characterise concentration changes in 29 selected metabolites following exposures of aquatic invertebrates, Gammarus pulex, to pharmaceuticals. Method performance revealed excellent linearity (R2>0.99), precision (0.1-19 %) and lower limits of detection (0.002-0.20 ng) for all metabolites studied. Three pharmaceuticals were selected representing the low, middle and high range of measured acute measured toxicities (of a total of 26 compounds). Gammarids were exposed to both the no-observed-adverse-effect-level and the lowest-observed-adverse-effect-level of triclosan (0.1 and 0.3 mg L-1), nimesulide (0.5 and 1.4 mg L-1) and propranolol (100 and 153 mg L-1) over 24 hrs. Quantitative metabolite profiling was then performed. Significant changes in metabolite concentrations relative to controls are presented and showed distinct clustered trends for each pharmaceutical. Approximately 37 % (triclosan), 33 % (nimesulide) and 46 % (propranolol) of metabolites showed statistically significant time-related effects. Observed changes are also discussed with respect to internal concentrations of the three pharmaceuticals measured using a method based on pulverised liquid extraction, solid phase extraction and LC-MS/MS. Potential metabolic pathways that may be affected by such exposures are also discussed. This represents the first study focussing on quantitative, targeted metabolomics of this lower trophic level benthic invertebrate that may elucidate biomarkers for future risk assessment.
Barron LP, McEneff GL, 2016, Gradient liquid chromatographic retention time prediction for suspect screening applications, A critical assessment of a generalised artificial neural network-based approach across 10 multi-residue reversed-phase analytical methods, Vol: 147, Pages: 261-270, ISSN: 0039-9140
For the first time, the performance of a generalised artificial neural network (ANN) approach for the prediction of 2492 chromatographic retention times (tR) is presented for a total of 1117 chemically diverse compounds present in a range of complex matrices and across 10 gradient reversed-phase liquid chromatography-(high resolution) mass spectrometry methods. Probabilistic, generalised regression, radial basis function as well as 2- and 3-layer multilayer perceptron-type neural networks were investigated to determine the most robust and accurate model for this purpose. Multi-layer perceptrons most frequently yielded the best correlations in 8 out of 10 methods. Averaged correlations of predicted versus measured tR across all methods were R2=0.918, 0.924 and 0.898 for the training, verification and test sets respectively. Predictions of blind test compounds (n=8-84 cases) resulted in an average absolute accuracy of 1.02±0.54 min for all methods. Within this variation, absolute accuracy was observed to marginally improve for shorter runtimes, but was found to be relatively consistent with respect to analyte retention ranges (~5%). Finally, optimised and replicated network dependency on molecular descriptor data is presented and critically discussed across all methods. Overall, ANNs were considered especially suitable for suspects screening applications and could potentially be utilised in bracketed-type analyses in combination with high resolution mass spectrometry.
Miller T, McEneff GL, Stott LC, et al., 2016, Assessing the reliability of uptake and elimination kinetics modelling approaches for estimating bioconcentration factors in the freshwater invertebrate, Gammarus pulex Thomas H. Miller, Gillian L. McEneff, Lucy C. Stott, Stewart F. Owen, Nicolas R. Bury, Leon P. Barron, Science of the Total Environment, Vol: 547, Pages: 396-404, ISSN: 0048-9697
This study considers whether the current standard toxicokinetic methods are an accurate and applicable assessment of xenobiotic exposure in an aquatic freshwater invertebrate. An in vivo exposure examined the uptake and elimination kinetics for eight pharmaceutical compounds in the amphipod crustacean, Gammarus pulex by measuring their concentrations in both biological material and in the exposure medium over a 96 h period. Selected pharmaceuticals included two anti-inflammatories (diclofenac and ibuprofen), two beta-blockers (propranolol and metoprolol), an anti-depressant (imipramine), an anti-histamine (ranitidine) and two beta-agonists (formoterol and terbutaline). Kinetic bioconcentration factors (BCFs) for the selected pharmaceuticals were derived from a first-order one-compartment model using either the simultaneous or sequential modelling methods. Using the simultaneous method for parameter estimation, BCF values ranged from 12 to 212. In contrast, the sequential method for parameter estimation resulted in bioconcentration factors ranging from 19 to 4533. Observed toxicokinetic plots showed statistically significant lack-of-fits and further interrogation of the models revealed a decreasing trend in the uptake rate constant over time for rantidine, diclofenac, imipramine, metoprolol, formoterol and terbutaline. Previous published toxicokinetic data for 14 organic micro-pollutants were also assessed and similar trends were identified to those observed in this study. The decreasing trend of the uptake rate constant over time highlights the need to interpret modelled data more comprehensively to ensure uncertainties associated with uptake and elimination parameters for determining bioconcentration factors are minimised.
Miller TH, McEneff GL, Brown RJ, et al., 2015, Pharmaceuticals in the freshwater invertebrate, Gammarus pulex, determined using pulverised liquid extraction, solid phase extraction and liquid chromatography-tandem mass spectrometry, Science of the Total Environment, Vol: 511, Pages: 153-160, ISSN: 0048-9697
The development, characterisation and application of a new analytical method for multi-residue PPCP determination in the freshwater amphipod, Gammarus pulex are presented. Analysis was performed using pulverised liquid extraction (PuLE), solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Qualitative method performance offered excellent limits of detection at <20ngg-1 for 18 out of 29 compounds. For quantitative application, linearity and precision were considered acceptable for 10 compounds across the ng-μgg-1 range (R2≥0.99; ≤20% relative standard deviation respectively). The method was applied to the analysis of G. pulex and river water sourced from six tributaries of the River Thames. Carbamazepine, diazepam, nimesulide, trimethoprim and warfarin were determined in G. pulex samples at low ngg-1 (dry weight) concentrations across these sites. Temazepam and diclofenac were also detected, but were not quantifiable. Six pharmaceuticals were quantified in surface waters across the eight sites at concentrations ranging from 3 to 344ngL-1. The possibility for confirmatory detection and subsequent quantification of pharmaceutical residues in benthic organisms such as G. pulex will enable further understanding on the susceptibility and ecological effects of PPCPs in the aquatic environment.
Munro K, Miller TH, Martins CPB, et al., 2015, Artificial neural network modelling of pharmaceutical residue retention times in wastewater extracts using gradient liquid chromatography-high resolution mass spectrometry data, Journal of Chromatography A, Vol: 1396, Pages: 34-44, ISSN: 0021-9673
The modelling and prediction of reversed-phase chromatographic retention time (tR) under gradient elution conditions for 166 pharmaceuticals in wastewater extracts is presented using artificial neural networks for the first time. Radial basis function, multilayer perceptron and generalised regression neural networks were investigated and a comparison of their predictive ability for model solutions discussed. For real world application, the effect of matrix complexity on tR measurements is presented. Measured tR for some compounds in influent wastewater varied by >1min in comparison to tR in model solutions. Similarly, matrix impact on artificial neural network predictive ability was addressed towards developing a more robust approach for routine screening applications. Overall, the best neural network had a predictive accuracy of <1.3min at the 75th percentile of all measured tR data in wastewater samples (<10% of the total runtime). Coefficients of determination for 30 blind test compounds in wastewater matrices lay at or above R2=0.92. Finally, the model was evaluated for application to the semi-targeted identification of pharmaceutical residues during a weeklong wastewater sampling campaign. The model successfully identified native compounds at a rate of 83±4% and 73±5% in influent and effluent extracts, respectively. The use of an HRMS database and the optimised ANN model was also applied to shortlisting of 37 additional compounds in wastewater. Ultimately, this research will potentially enable faster identification of emerging contaminants in the environment through more efficient post-acquisition data mining.
Schnell S, Bawa-Allah K, Otitoloju A, et al., 2015, Environmental monitoring of urban streams using a primary fish gill cell culture system (FIGCS), Ecotoxicology and Environmental Safety, Vol: 120, Pages: 279-285, ISSN: 0147-6513
The primary fish gill cell culture system (FIGCS) is an in vitro technique which has the potential to replace animals in whole effluent toxicity tests. In the current study FIGCS were transported into the field and exposed to filtered (0.2μm) river water for 24h from 4 sites, on 2 different sampling dates. Sites 1 and 2 are situated in an urban catchment (River Wandle, London, UK) with site 1 downstream of a sewage treatment work; site 3 is located in a suburban park (River Cray, Kent, UK), and site 4 is more rural (River Darent, Kent, UK). The change in transepithelial electrical resistance (TER), the expression of the metal responsive genes metallothionein A (mta) and B (mtb), cytochrome P450 1A1 (cyp1a1) and 3A27 (cyp3a27), involved in phase 1 metabolism, were assessed following exposure to sample water for 24h. TER was comparable between FIGCS exposed to 0.2μm filtered river water and those exposed to synthetic moderately soft water for 24h. During the first sampling time, there was an increase in mta, cyp1a1 and cyp3a27 gene expression in epithelium exposed to water from sites 1 and 2, and during the second sampling period an increase in cyp3a27 gene expression at sites 1 and 4. Urban river water is a complex mixture of contaminants (e.g., metals, pesticides, pharmaceuticals and polyaromatic hydrocarbons) and the increase in the expression of genes encoding mta, cyp1a1 and cyp3a27 in FIGCS is indicative of the presence of biologically active pollutants.
Gilchrist ES, Nesterenko PN, Smith NW, et al., 2015, Organic solvent and temperature-enhanced ion chromatography-high resolution mass spectrometry for the determination of low molecular weight organic and inorganic anions, ANALYTICA CHIMICA ACTA, Vol: 865, Pages: 83-91, ISSN: 0003-2670
There has recently been increased interest in coupling ion chromatography (IC) to high resolution mass spectrometry (HRMS) to enable highly sensitive and selective analysis. Herein, the first comprehensive study focusing on the direct coupling of suppressed IC to HRMS without the need for post-suppressor organic solvent modification is presented. Chromatographic selectivity and added HRMS sensitivity offered by organic solvent-modified IC eluents on a modern hyper-crosslinked polymeric anion-exchange resin (IonPac AS18) are shown using isocratic eluents containing 5-50. mM hydroxide with 0-80% methanol or acetonitrile for a range of low molecular weight anions (<165. Da). Comprehensive experiments on IC thermodynamics over a temperature range between 20-45. °C with the eluent containing up to 60% of acetonitrile or methanol revealed markedly different retention behaviour and selectivity for the selected analytes on the same polymer based ion-exchange resin. Optimised sensitivity with HRMS was achieved with as low as 30-40% organic eluent content. Analytical performance characteristics are presented and compared with other IC-MS based works. This study also presents the first application of IC-HRMS to forensic detection of trace low-order anionic explosive residues in latent human fingermarks.
Bade R, Bijlsma L, Miller TH, et al., 2015, Suspect screening of large numbers of emerging contaminants in environmental waters using artificial neural networks for chromatographic retention time prediction and high resolution mass spectrometry data analysis, Science of the Total Environment, Vol: 538, Pages: 934-941, ISSN: 0048-9697
The recent development of broad-scope high resolution mass spectrometry (HRMS) screening methods has resulted in a much improved capability for new compound identification in environmental samples. However, positive identifications at the ng/L concentration level rely on analytical reference standards for chromatographic retention time (tR) and mass spectral comparisons. Chromatographic tR prediction can play a role in increasing confidence in suspect screening efforts for new compounds in the environment, especially when standards are not available, but reliable methods are lacking. The current work focuses on the development of artificial neural networks (ANNs) for tR prediction in gradient reversed-phase liquid chromatography and applied along with HRMS data to suspect screening of wastewater and environmental surface water samples. Based on a compound tR dataset of >500 compounds, an optimized 4-layer back-propagation multi-layer perceptron model enabled predictions for 85% of all compounds to within 2min of their measured tR for training (n=344) and verification (n=100) datasets. To evaluate the ANN ability for generalization to new data, the model was further tested using 100 randomly selected compounds and revealed 95% prediction accuracy within the 2-minute elution interval. Given the increasing concern on the presence of drug metabolites and other transformation products (TPs) in the aquatic environment, the model was applied along with HRMS data for preliminary identification of pharmaceutically-related compounds in real samples. Examples of compounds where reference standards were subsequently acquired and later confirmed are also presented. To our knowledge, this work presents for the first time, the successful application of an accurate retention time predictor and HRMS data-mining using the largest number of compounds to preliminarily identify new or emerging contaminants in wastewater and surface waters.
Boonjob W, Sklenářová H, Barron L, et al., 2015, Renewable sorbent material for solid phase extraction with direct coupling of sequential injection analysis-bead injection to liquid chromatography-electrospray ionization tandem mass spectrometry, ANALYTICAL AND BIOANALYTICAL CHEMISTRY, Vol: 407, Pages: 5719-5728, ISSN: 1618-2642
The use of small scale renewable sorbent material for automated solid phase extraction of multi-residue pharmaceuticals in environmental samples exploiting the sequential injection analysis-bead injection with direct coupling to liquid chromatography-electrospray ionization tandem mass spectrometry (SIA-BI-μSPE-LC-ESI-MS/MS) is presented to determine beta-blockers, namely atenolol, sotalol, pindolol, acebutolol, timolol, metoprolol, labetalol, carazolol, propranolol and betaxolol. These compounds yielded the same product ions, therefore were affected in terms of quantification when flow injection analysis-mass spectrometry (FIA-MS) was used. Thus, analytes and matrix present in the sample travel together into the ionization source which can seriously affect the ionization efficiency and analyte signals due to monitoring over a short time period. [Figure not available: see fulltext.]
Baker D, Barron L, Kasprzyk-Hordern B, 2014, Illicit and pharmaceutical drug consumption estimated via wastewater analysis. Part A: Chemical analysis and drug use estimates, Chemical analysis and drug use estimates, Vol: 487, Pages: 629-641, ISSN: 0048-9697
This paper presents, for the first time, community-wide estimation of drug and pharmaceuticals consumption in England using wastewater analysis and a large number of compounds. Among groups of compounds studied were: stimulants, hallucinogens and their metabolites, opioids, morphine derivatives, benzodiazepines, antidepressants and others. Obtained results showed the usefulness of wastewater analysis in order to provide estimates of local community drug consumption. It is noticeable that where target compounds could be compared to NHS prescription statistics, good comparisons were apparent between the two sets of data. These compounds include oxycodone, dihydrocodeine, methadone, tramadol, temazepam and diazepam. Whereas, discrepancies were observed for propoxyphene, codeine, dosulepin and venlafaxine (over-estimations in each case except codeine). Potential reasons for discrepancies include: sales of drugs sold without prescription and not included within NHS data, abuse of a drug with the compound trafficked through illegal sources, different consumption patterns in different areas, direct disposal leading to over estimations when using parent compound as the drug target residue and excretion factors not being representative of the local community. It is noticeable that using a metabolite (and not a parent drug) as a biomarker leads to higher certainty of obtained estimates. With regard to illicit drugs, consistent and logical results were reported. Monitoring of these compounds over a one week period highlighted the expected recreational use of many of these drugs (e.g. cocaine and MDMA) and the more consistent use of others (e.g. methadone).
McEneff G, Barron L, Kelleher B, et al., 2014, A year-long study of the spatial occurrence and relative distribution of pharmaceutical residues in effluent, receiving marine waters and marine bivalves, Science of the Total Environment, Vol: 476-477, Pages: 317-326, ISSN: 0048-9697
Reports concerning the quantitative analysis of pharmaceuticals in marine ecosystems are somewhat limited. It is necessary to determine pharmaceutical fate and assess any potential risk of exposure to aquatic species and ultimately, seafood consumers. In the work presented herein, analytical methods were optimised and validated for the quantification of pharmaceutical residues in wastewater effluent, receiving marine waters and marine mussels (Mytilus spp.). Selected pharmaceuticals included two non-steroidal anti-inflammatory drugs (NSAIDs) (diclofenac and mefenamic acid), an antibiotic (trimethoprim), an antiepileptic (carbamazepine) and a lipid regulator (gemfibrozil). This paper also presents the results of an in situ study in which caged Mytilus spp. were deployed at three sites on the Irish coastline over a 1-year period. In water samples, pharmaceutical residues were determined using solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction of pharmaceuticals from mussel tissues used an additional pressurised liquid extraction (PLE) step prior to SPE and LC-MS/MS. Limits of quantification between 15 and 225 ng.L-1 were achieved in wastewater effluent, between 3 and 38 ng.L-1 in marine surface water and between 4 and 29 ng.g(-1) dry weight in marine mussels. Method linearity was achieved for pharmaceuticals in each matrix with correlation coefficients of R-2 >= 0.976. All five selected pharmaceuticals were quantified in wastewater effluent and marine surface waters. This work has demonstrated the susceptibility of the Mytilus spp. to pharmaceutical exposure following the detection of pharmaceutical residues in the tissues of this mussel species at measurable concentrations.
Barron L, 2014, The Chartered Society of Forensic Sciences - Impacts on R&D?, Science and Justice, Vol: 54, ISSN: 1355-0306
Barron L, Gilchrist E, 2014, Ion chromatography-mass spectrometry, a review of recent technologies and applications in forensic and environmental explosives analysis, Vol: 806, Pages: 27-54, ISSN: 0003-2670
The development and application of ion chromatography (IC) coupled to mass spectrometry (MS) is discussed herein for the quantitative determination of low-order explosives-related ionic species in environmental and forensic sample types. Issues relating to environmental explosives contamination and the need for more confirmatory IC-MS based applications in forensic science are examined. In particular, the compatibility of a range of IC separation modes with MS detection is summarised along with the analytical challenges that have been overcome to facilitate determinations at the ng–μg L−1 level. Observed trends in coupling IC to inductively coupled plasma and electrospray ionisation mass spectrometry form a particular focus. This review also includes a discussion of the relative performance of reported IC-MS methods in comparison to orthogonal ion separation-based, spectrometric and spectroscopic approaches to confirmatory detection of low-order explosives. Finally, some promising areas for future research are highlighted and discussed with respect to potential IC-MS applications.
Barron L, 2013, The Final Frontier, Science and Justice, Vol: 53, Pages: 373-374, ISSN: 1355-0306
Hart K, Oppenheimer S, Moran B, et al., 2013, CO2 uptake by a soil microcosm, SOIL BIOLOGY AND BIOCHEMISTRY, Vol: 57, Pages: 615-624, ISSN: 0038-0717
Sequestration of CO2 via biological sinks is a matter of great scientific importance due to the potential lowering of atmospheric CO2. In this study, a custom built incubation chamber was used to cultivate a soil microbial community to instigate chemoautotrophy of a temperate soil. Real-time atmospheric CO2 concentrations were monitored and estimations of total CO2 uptake were made. After careful background flux corrections, 4.52 ± 0.05 g CO2 kg−1 dry soil was sequestered from the chamber atmosphere over 40 h. Using isotopically labelled 13CO2 and GCMS–IRMS, labelled fatty acids were identified after only a short incubation, hence confirming CO2 sequestration for soil. The results of this in vivo study provide the ground work for future studies intending to mimic the in situ environment by providing a reliable method for investigating CO2 uptake by soil microorganisms.
Szomborg K, Jongekrijg F, Gilchrist E, et al., 2013, Residues from low-order energetic materials, the comparative performance of a range of sampling approaches prior to analysis by ion chromatography, Vol: 233, Pages: 55-62, ISSN: 0379-0738
A quantitative study of common forensic evidence collection devices for the recovery of low-explosive residues from non-porous glass and plastic is presented herein. Swabbing materials including cotton, rayon, Nomex® (poly(isophthaloylchloride/m-phenylenediamine)), Teflon/Teflon-coated fibreglass (polytetrafluoroethylene) and adhesive-coated tapes were used to collect known quantities of up to 14 forensically relevant inorganic and organic anion and cation species from both surfaces. Analysis was performed using two validated ion chromatography methods. This study revealed that all swabs and surfaces contributed highly variable levels of interfering ionic species and that swabbing materials showed variance in the quantities and total number of analytes recovered from both surfaces. Teflon and Nomex® materials demonstrated the most promise due to their ability to collect and release analytes into simple extraction solvents as well as displaying relatively low endogenous interference. In parallel, the ability to extract residue directly from both surfaces via the addition of a suitable extraction solvent was investigated instead of swabbing. This work highlights that direct solvent extraction from a surface should be considered as an alternative approach, especially for small areas or objects. To the best of our knowledge, this work represents the most comprehensive study of the efficiencies of sample collection technologies for low-explosive residues prior to analysis by ion chromatography.
Miller TH, Musenga A, Cowan DA, et al., 2013, Prediction of chromatographic retention time in high-resolution anti-doping screening data using artificial neural networks, Analytical Chemistry, Vol: 85, Pages: 10330-10337, ISSN: 0003-2700
The computational generation of gradient retention time data for retrospective detection of suspected sports doping species in postanalysis human urine sample data is presented herein. Retention data for a selection of 86 compounds included in the London 2012 Olympic and Paralympic Games drug testing schedule were used to train, verify, and test a range of computational models for this purpose. Spiked urine samples were analyzed using solid phase extraction followed by ultrahigh-pressure gradient liquid chromatography coupled to electrospray ionization high-resolution mass spectrometry. Most analyte retention times varied ≤0.2 min over the relatively short runtime of 10 min. Predicted retention times were within 0.5 min of experimental values for 12 out of 15 blind test compounds (largest error: 0.97 min). Minimizing the variance in predictive ability across replicate networks of identical architecture is presented for the first time along with a quantitative discussion of the contribution of each selected molecular descriptor toward the overall predicted value. The performance of neural computing predictions for isobaric compound retention time is also discussed. This work presents the application of neural networks to the prediction of gradient retention time in archived high-resolution urine analysis sample data for the first time in the field of anti-doping.
McEneff G, Barron L, Kelleher B, et al., 2013, The determination of pharmaceutical residues in cooked and uncooked marine bivalves using pressurised liquid extraction, solid phase extraction and liquid chromatography-tandem mass spectrometry, ANALYTICAL AND BIOANALYTICAL CHEMISTRY, Vol: 405, Pages: 9509-9521, ISSN: 1618-2642
An optimised and validated method for the determination of pharmaceutical residues in blue mussels (Mytilus spp.) is presented herein, as well as an investigation of the effect of cooking (by steaming) on any potential difference in human exposure risk. Selected pharmaceuticals included two non-steroidal anti-inflammatory drugs (diclofenac and mefenamic acid), an antibiotic (trimethoprim), an anti-epileptic (carbamazepine) and a lipid regulator (gemfibrozil). An in vivo exposure experiment was set up in the laboratory in which mussels were exposed either directly by injection (10 ng) or daily through spiked artificial seawater (ASW) over 96 h. In liquid matrices, pharmaceutical residues were either determined using liquid chromatography–tandem mass spectrometry (LC-MS/MS) directly, or in combination with solid-phase extraction (SPE) for analyte concentration purposes. The extraction of pharmaceuticals from mussel tissues used an additional pressurised liquid extraction step prior to SPE and LC-MS/MS. Limits of quantification of between 2 and 46 ng L−1 were achieved for extracted cooking water and ASW, between 2 and 64 μg L−1 for ASW in exposure tanks, and between 4 and 29 ng g−1 for mussel tissue. Method linearities were achieved for pharmaceuticals in each matrix with correlation coefficients of R 2 > 0.975. A selection of exposed mussels was also cooked (via steaming) and analysed using the optimised method to observe any effect on detectable concentrations of parent pharmaceuticals present. An overall increase in pharmaceutical residues in the contaminated mussel tissue and cooking water was observed after cooking.
Love C, Gilchrist E, Smith N, et al., 2013, Detection of anionic energetic material residues in enhanced fingermarks on porous and non-porous surfaces using ion chromatography, Forensic Science International, Vol: 231, Pages: 150-156, ISSN: 0379-0738
The ability to link criminal activity and identity using validated analytical approaches can be of great value to forensic scientists. Herein, the factors affecting the recovery and detection of inorganic and organic energetic material residues within chemically or physically enhanced fingermarks on paper and glass substrates are presented using micro-bore anion exchange chromatography with suppressed conductivity detection. Fingermarks on both surfaces were enhanced using aluminium powder or ninhydrin after spiking with model test mixtures or through contact with black-powder substitutes. A quantitative study of the effects of environmental/method interferences, the sweat matrix, the surface and the enhancement technique on the relative anion recovery of forensically relevant species is presented. It is shown that the analytical method could detect target analytes at the nanogram level even within excesses of enhancement reagents and their reaction products when using solid phase extraction and/or microfiltration. To our knowledge, this work demonstrates for the first time that ion chromatography can detect anions in energetic materials within fingermarks on two very different surfaces, after operational enhancement techniques commonly used by forensic scientists and police have been applied.
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