Ultrasound-Assisted Extraction (UAE), and UHPLC–MS/MS Methodology for the Pharmaceutical Multiresidue Extraction and Analysis of Agricultural Soil Samples

Using reclaimed water for irrigation is an effective strategy in semi-arid regions facing water scarcity. However, this water may contain pharmaceutical residues, posing potential environmental and health risks. To ensure sustainable reuse, it is essential to study how these substances accumulate in soil and transfer to crops. The aim of this research was to develop and optimise a rapid Ultrasound-Assisted Extraction method combined with Ultra-High-Performance Liquid Chromatography–tandem Mass Spectrometry for quantifying 23 pharmaceuticals in non-cultivated soil. Following optimisation, 18 compounds were successfully extracted using a MeOH:H2O ratio of 75:25. The detection and quantification limits were found to range from 0.52 to 0.5 ng·g−1 and 1.75 to 35 ng·g−1, respectively. The matrix effects and recoveries varied by compounds’ type and concentration, but most results were acceptable. The evidence suggested that some drugs underwent microbial degradation. Soil irrigated with reclaimed water via subsurface drip since 2012 occasionally contained four pharmaceuticals (caffeine, carbamazepine, tamoxifen, and venlafaxine) at low concentrations, while others were absent. This indicates the capacity of soil to act as a barrier, and highlights the importance of proper water management. The study concludes that reclaimed water reuse is safe if supported by efficient treatment and management, offering a promising approach for long-term sustainability in water-scarce regions.