Condensed Phase Membrane Introduction Mass Spectrometry with Direct Electron Ionization: On-line Measurement of PAHs in Complex Aqueous Samples

Polycyclic aromatic hydrocarbons (PAHs) are USEPA regulated priority pollutants. Their low aqueous solubility requires very sensitive analytical methods for their detection, typically involving pre-concentration steps. Presented is the first demonstrated 'proof of concept' use of condensed phase membrane introduction mass spectrometry (CP-MIMS) coupled with direct liquid electron ionization (DEI) for the direct, on-line measurement of PAHs in aqueous samples. DEI is very well suited for the ionization of PAHs and other non-polar compounds, and is not significantly influenced by the co-elution of matrix components. Linear calibration data for low ppb levels of aqueous naphthalene, anthracene and pyrene is demonstrated, with measured detection limits of 4 ppb. Analytical response times (t10-90% signal rise) ranged from 2.8 minutes for naphthalene to 4.7 minutes for pyrene. Both intra and inter day reproducibility has been assessed (< 3 % and 5 % RSD, respectively). Direct measurements of ppb level PAHs spiked in a variety of real, complex environmental sample matrices is examined, including natural waters, sea waters, and a hydrocarbon extraction production waste water sample. For these spiked, complex samples, direct PAH measurement by CP-MIMS-DEI yielded minimal signal suppression from sample