Improved Detection Limits for Polycyclic Aromatic Hydrocarbons (PAHs) in Soil and Sediments by Gas Chromatography-Mass Spectrometry (GC-MS) and Pseudo-Multiple Reaction Monitoring (PMRM)

Polycyclic aromatic hydrocarbons (PAHs) in soil pose significant analytical challenges due to matrix complexity, low concentrations, and co-extracted interferents. Conventional gas chromatography-mass spectrometry (GC-MS) methods suffer from limited sensitivity and selectivity, particularly for high-molecular-weight PAHs with stable molecular ions that resist fragmentation. Here, we present a novel gas chromatography-tandem mass spectrometry (GC-MS/MS) method using pseudo-multiple reaction monitoring (PMRM) coupled with an optimized extraction protocol for precise quantification of 16 USEPA priority PAHs in soil. By exploiting the inherent stability of PAH molecular ions ([M]+), PMRM achieved 3.1–4.8 times lower detection limits than traditional selected ion monitoring (SIM) while resolving critical isomer pairs (e.g., phenanthrene/anthracene, R > 1.5) through time-segmented collision energy (CE) optimization (5–25 eV). A streamlined extraction using acetonitrile modified with anhydrous Na2SO4 eliminated labor-intensive cleanup, achieving >85% recovery across a wide logKow range (3.37–6.50). The PMRM strategy enhanced signal-to-noise ratios by collisional focusing and differential interference fragmentation, enabling direct injection of crude extracts without compromising sensitivity. This approach addresses long-standing limitations in PAH analysis, offering a robust, high-throughput solution for environmental monitoring and regulatory compliance, with potential applications to other structurally stable pollutants.