Determination of 16 emerging organic pollutants in sea sand using a modified QuEChERS method combined with UHPLC-MS/MS

Emerging organic pollutants (EOPs), including pharmaceuticals, personal care products, pesticides, and industrial chemicals, are gaining attention due to their increasing presence in the environment and limited understanding of their impacts. This study developed and validated a method to determine 16 EOPs in marine sand, covering 4 pharmaceuticals, 8 hormones, 2 phenols, a UV filter, and a habit consumption compound. The method combines a modified QuEChERS method with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Validation included recovery, reproducibility, linearity, quantification limits, and matrix effects. Recoveries were assessed using sand from two beaches in Tenerife (Canary Islands, Spain), showing relative recoveries between 63.3 % and 110.4 %, and RSDs from 3.0 % to 10.6 %. Limits of quantification (LOQs) ranged from 0.026 to 0.441 ng/g, highlighting the method's sensitivity. Matrix-matched calibration revealed general signal suppression in both sand types. The validated method was applied to samples from three beaches, collected from dry and wet zones. Caffeine, oxybenzone, and bisphenol-A were found in all samples, often at concentrations well above their LOQs (0.098-9.011, 0.160-10.236, and 0.187-5.105 ng/g, respectively). Some variation in contaminant levels was observed depending on the moisture content of the sand. This study provides a reliable analytical approach for determining trace levels of EOPs in marine sands and contributes to the understanding of their occurrence in coastal environments.