Evaluation of Analytical Methods for PFAS and Pharmaceuticals in Water using Direct Injection and Online SPE LC-MS/MS

This study developed analytical methods for quantifying 39 per- and polyfluoroalkyl substances (PFAS) and 23 pharmaceuticals in water samples using direct injection and online solid-phase extraction (online SPE) coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS). The performance of the online SPE method was compared with that of direct injection. For PFAS, online SPE achieved lower method detection limits (MDLs; 0.1794.72 ng/L) than direct injection (3.2731.3 ng/L). Similarly, for pharmaceuticals, MDLs obtained with online SPE (0.0590.314 ng/L) were lower than those from direct injection (1.0956.8 ng/L). Both methods met established analytical criteria, showing acceptable accuracy (70130%) and precision (≤20%). The optimized method was applied to water samples from the Nakdong River in Korea. Among the 39 PFAS, only one compound was detected via direct injection, whereas eight compounds were identified using online SPE. For pharmaceuticals, direct injection detected 10 compounds, while online SPE identified 15. Additionally, the detection frequency across sampling sites was similar to or higher than that of online SPE compared to direct injection. Overall, online SPE proved more effective for detecting PFAS and pharmaceuticals in river water than direct injection, offering additional advantages in labor efficiency, cost-effectiveness, and suitability for routine water quality monitoring programs.