Quantitative Analysis of Polycyclic Aromatic Hydrocarbons in Water in the Low-Nanogram per Liter Range with Two-Step Laser Mass Spectrometry

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are of major concern in all environmental compartments due to the mutagenic and carcinogenic properties of many PAHs. Two-step laser mass spectrometry (L2MS) is a sensitive and selective method to measure PAHs in complex solid matrixes. However, in most studies, L2MS was used for qualitative or semiquantitative analyses. Here we present for the first time a quantitative method analyzing PAHs in water at the nanogram per liter level. PAHs are extracted from a 30-mL water sample with a solid PVC membrane, which is then directly measured by L2MS without further treatment. Detection limits are in the low-nanogram per liter range (2-125 ng/L) for skeletal three- to six-ring PAHs. Extraction efficiencies of this method are between 75 and 90%. In a first application, samples from a wastewater treatment plant were measured, showing that microbial activities efficiently decrease PAH concentrations by 75-90%.

Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield, Antarctica

“…These filters were not investigated for micrometeorite content, but were analyzed for PAHs that would possibly be present in the particulate matter. Dissolved PAHs were extracted from the resulting filtrates using solidphase extraction with polyvinyl chloride (PVC) membranes (Emmenegger et al 2003). The membranes were attached to a stainless steel holder and dipped into the aqueous solutions for 15 h. at room temperature in the darkness.…”

“…PAHs were measured using a custom-made two-step laser mass spectrometry (L2MS) system (Haefliger et al 1998;Emmenegger et al 2003). A CO 2 laser (Alltec 853 MS) with a wavelength of 10.6 µm and 5 mJ/shot was used for desorption of the molecules from the substrate.…”

“…In contrast to the filter spectra (particulate matter), the signals in the L2MS spectra of the PVC membranes (solid solution) were at blank level. From the calibration curves obtained with the L2MS instrument (Emmenegger et al 2003;Emmenegger 2006), the dissolved PAH concentrations in the ice samples were determined to be below 10-80 pg/l (depending on both the concentration factors of the individual samples and the mass signal intensities). These values are in the same range of the upper limit determined for polar ice from Greenland (8 to 460 pg of PAHs/kg ice) (Jaffrezo et al 1994;Masclet et al 1995;Clemett et al 1998).…”

“…PAHs in liquid matrices are a special challenge for L2MS, because the sample has to be in solid form to be analyzed. In this project PAHs were extracted and concentrated from water samples with a solid PVC membrane containing an internal standard Emmenegger et al 2003). Limits of detection in the low nanogram per liter (ng/l) range were achieved.…”

Photoionisation and photodissociation studies of nonvolatile organic molecules by synchrotron VUV photoionisation mass spectrometry and theoretical calculations

“…The L2MS uses laser for desorption followed by the resonance-enhanced multiphoton ionisation (REMPI) with laser or single-photon ionisation (SPI) with laser/discharge lamp to produce ions [32]. Due to the 'soft' ionisation, especially for SPI, the L2MS requires almost no sample preparation [33] and has proven to be a powerful analytical technique for characterising a wide range of molecular systems with high sensitivity [34][35][36][37][38][39][40][41][42][43][44][45][46].…”