b'23Investigating the occurrence of anticoccidial agrochemicals in Irish groundwaters: preliminary findingsMooney D1,2,3,5, Danaher M2, Richards K3,5, Gill L4,5, Mellander P-E3,6 and Coxon C1,51Geology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland2Food Safety Department, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland3Crops, Environment and Land Use Programme, Teagasc, Johnstown Castle EnvironmentResearch Centre, Wexford, Co. Wexford, Ireland4Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Dublin 2, Ireland5Groundwater Challenge, Irish Centre for Research in Applied Geosciences (iCRAG)6Agricultural Catchments Programme, Teagasc, Johnstown Castle Environment ResearchCentre, Wexford, Co. Wexford, IrelandDue to increased intensification of the food production system, agrochemicals includingveterinary pharmaceuticals have become a critical component in animal husbandry.Administration of such compounds can potentially lead to their occurrence in the environment. This work presents investigations of a particular group of agrochemicals called anticoccidials, which are used to control coccidiosis and other protozoan infections in food producing animals. They are licensed in the EU both as veterinary drugs for therapeutic treatment and/ or as feed additives, with primary prophylactic use in poultry production. Excretion in manure andsubsequent landspreading provides a potential pathway to groundwater. There is limitedinformation available on the fate and occurrence of these compounds in environmental waters and as a result, these substances are considered to be potential emerging organic contaminants of concern. The aim of this work was to develop a comprehensive method for thedetermination of commonly used anticoccidials in environmental water samples, in order toinvestigate the occurrence of these contaminants in an Irish groundwater setting.A multi-residue method based on Solid Phase Extraction (SPE) with Ultra High PerformanceLiquid Chromatography Tandem Mass Spectrometry (UHPLC-MS/MS) detection was developed for the quantitative determination of 26 anticoccidials in water. This method was applied in acomprehensive spatial study whereby 109 samples (63 borehole and 46 spring samples),representative of the different karst and fractured aquifer categories in Ireland, were sampled and analysed during November 2018. The preliminary findings of this study are presented here, which show detections of up to 7 different anticoccidial compounds at 24 % of sites sampled(26 of 109).Keywords: agro-chemical; anticoccidials; emerging organic contaminant; groundwater; karst67'