Portable Mass Spectrometry for In-Field Real-Time Water Pollution Monitoring: Validation and Pilot Study in Danube-Tisa-Danube Irrigation System.

Continuous, real-time monitoring of volatile organic compounds (VOCs) in surface water is critical for environmental protection, yet conventional laboratory Gas Chromatography-Mass Spectrometry (GC-MS) suffers from analyte loss during sample transport. This study field-validates a portable Membrane Inlet Mass Spectrometry (MIMS) system for direct, on-site monitoring of seven target VOCs (benzene, toluene, xylenes, chlorobenzene, 1,2-dichloroethane, trichloroethylene, and tetrachloroethylene). Laboratory validation established limits of detection between 4 and 8 µg/L, linearity (R2 > 0.98), and acceptable precision and accuracy per AOAC guidelines, benchmarked against headspace GC-MS. In-field testing at 36 locations across the Danube-Tisa-Danube (DTD) irrigation canal demonstrated system robustness. Baseline canal samples remained below the detection limits, but real-time MIMS successfully identified localized benzene and toluene contamination near a gasoline station. On-site MIMS detected higher VOC concentrations than delayed laboratory GC-MS, demonstrating its key advantage in preventing sampling volatilization losses. Portable MIMS proves to be a powerful, rapid screening tool for continuous aquatic environmental monitoring.