Determination of organic contaminants in groundwater from Anaga Rural Park and El Teide National Park (Canary Islands, Spain) by ultra-high-performance liquid chromatography-tandem mass spectrometry

Organic contaminants have attracted increasing attention due to their widespread presence and potential impacts on environmental and human health, particularly in groundwater resources used for drinking purposes. In this study, the occurrence of 18 organic contaminants, including pesticides, pharmaceuticals, hormones, and antibiotics, was evaluated in groundwater samples collected from wells, galleries, and springs located in Anaga Rural Park and El Teide National Park (Tenerife, Canary Islands), two protected volcanic environments of high ecological value. A simple and sensitive analytical method based on automated solid-phase extraction followed by ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. Method validation included linearity, limits of quantification (LOQs), precision, accuracy, and matrix effects. Two independent validations were performed to account for matrix variability between well waters and combined gallery and spring waters. Recovery values within acceptable ranges and LOQs at the ng/L level demonstrated adequate accuracy and sensitivity for trace level determination of target compounds in heterogeneous groundwater matrices. The validated method was applied to 26 groundwater samples analysed in duplicate. Several contaminants were detected, including myclobutanil, tebuconazole, oxolinic acid, caffeine, and carbamazepine, with concentrations generally in the ng/L range. Although most compounds were detected at trace levels, their presence indicates potential anthropogenic influence, likely associated with agricultural activities, wastewater infiltration, and other diffuse pollution sources. This study provides one of the first multi-class assessments of organic contaminants in groundwater from protected volcanic aquifers in Tenerife, contributing to a better understanding of groundwater vulnerability and supporting future monitoring and water management strategies in protected areas.