title: Artificial neural network modelling of pharmaceutical residue retention times in wastewater extracts using gradient liquid chromatography-high resolution mass spectrometry data.
abstract: 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 R(2)=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.
authors.affiliation: Analytical & Environmental Sciences Division, King's College London, 150 Stamford Street, SE1 9NH London, United Kingdom.
authors.forename: Kelly
authors.initials: K
authors.lastname: Munro
authors.affiliation: Analytical & Environmental Sciences Division, King's College London, 150 Stamford Street, SE1 9NH London, United Kingdom.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Miller
authors.affiliation: Thermo Fisher Scientific, 355 River Oaks Parkway, San Jose, CA 95134, USA.
authors.forename: Claudia P B
authors.initials: CP
authors.lastname: Martins
authors.affiliation: Thermo Fisher Scientific, Tudor Road, Runcorn, United Kingdom.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Edge
authors.affiliation: Analytical & Environmental Sciences Division, King's College London, 150 Stamford Street, SE1 9NH London, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Cowan
authors.affiliation: Analytical & Environmental Sciences Division, King's College London, 150 Stamford Street, SE1 9NH London, United Kingdom. Electronic address: leon.barron@kcl.ac.uk.
authors.forename: Leon P
authors.initials: LP
authors.lastname: Barron
mesh_terms: D056148:Chromatography, Reverse-Phase / Q000379:methods*; D004350:Drug Residues / Q000032:analysis*; D013058:Mass Spectrometry; D016571:Neural Networks, Computer; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Artificial neural networks; High resolution mass spectrometry; Retention time prediction; Reversed-phase liquid chromatography; Semi-targeted detection