Accurate quantification of PAHs in water in the presence of dissolved humic acids using isotope dilution mass spectrometry

Abstract

The effect of dissolved humic acids on the recovery of PAHs from water samples has been investigated using a commercially available humic acid preparation as colloid model and a mixture containing the 16 EPA PAHs. The presence of humic acid reduced the extraction efficiency down to between 10 and 75%. An analytical protocol was therefore developed for the accurate determination of PAHs in the presence of humic acids based on isotope dilution mass spectrometry. The procedure compensates for losses due to sorption of PAHs and can be used for the determination of the total PAH concentration in water, i.e. dissolved PAHs plus PAHs adsorbed on colloids. To obtain reliable estimates it is essential to allow a certain time for equilibration between the isotope spike and the aqueous matrix which may vary between 5 and 24 h, in correlation with the water solubility of PAHs. The protocol allows one to recover the 16 PAHs studied at 94 to 105%. The expanded uncertainty of the measurements was 5-7% for all PAHs. Liquid-liquid extraction and solid-phase extraction in combination with the developed isotope dilution protocol performed equally well for the quantification of PAHs from water samples rich in colloidal material.

Cloud-point extraction of selected polycyclic aromatic hydrocarbons by nonionic surfactants

“…Ideally, the preconcentration factor for each individual PAH should be the same. However, with trace amounts of PAHs at 600 and 60 ppb initially spiked in this work, some uncertainty arising from sample handling and experimental procedures cannot be avoided [29]. Indeed, the recovery efficiency for each PAH is satisfactory.…”

Sorption of PAHs to Colloid Dispersions of Humic Substances in Water

“…HSs can complicate many environmental pollutants, such as polycyclic aromatic hydrocarbons (PAHs) (LeBoeuf and Weber, 2000;Yang et al, 2001;Sabbah et al, 2004;Bercaru et al, 2006;Mashayekhi et al, 2006;Ping et al, 2006). PAHs were selected because of their planar configuration as opposed to other bulky, three-dimensional molecules (for instance, different pesticides).…”

Interaction of 15 priority substances for water monitoring at ng L−1 levels with glass, aluminium and fluorinated polyethylene bottles for the containment of water reference materials

“…Two bottles of each volume were taken after 3, 24, 72 and 192 h, respectively. The content was poured into pre-cleaned amber glass bottles, and the internal standard was added and left to equilibrate for 24 h [26]. Thus, the difference between the added and the determined concentration of the target compound would be mainly due to losses by adsorption onto the container walls of the first bottle.…”

“…The MS detector was operated in selected ion monitoring using the identification ions (m/z) listed elsewhere [26]. Quantification of PAHs was performed using the internal standard method.…”