Water probably is the most important transport medium for inorganic and organic pollutants, being
discharged either directly (communal sewage, industrial effluents) or indirectly (application of pesticides, atmospheric deposition) into aquatic systems. In order to study the fate of contaminants and to assess their
ecotoxicological impact, it is inevitable to determine concentrations of these substances and their transformation products (TPs) in (different types of) water. We have specialised on the determination of organic
contaminants and their transformation products at ultra-trace levels (pg/L to ng/L-range), mainly in marine but also in limnic ecosystems. We were/are applying the following extraction technologies:
Solid-phase extraction (SPE)
In addition to the use of standard SPE-cartridges (PS-DVB, C18) we have developed special filtration/extraction gear for the extraction of large volumes of water (10-100 L) at
high flow rates (500 mL/min). The application of hyper-crosslinked polystyrene-divinylbenzene (PS-DVB) sorbents allows the extraction of a broad range of organic compounds. It is especially well suited for medium polar
to readily water-soluble substances, e.g., triazines and TPs, phenols, carboxylic acids and even sugars. The technique is currently applied to the determination of pharmaceuticals and personal care products (PPCPs) from
marine and estuarine waters.
Liquid-liquid extraction (LLE)
LLE has been used in our group for the extraction of medium polar to highly lipophilic compounds. It has mainly
been performed on 10 L-samples with n-hexane as solvent, including the investigation of contaminants such as polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs), triazine herbicides (atrazine,
simazine, terbutylazine, irgarol etc.), phenoxyalkanoic acid herbicides (after in-situ derivatisation), nitroaromatic compounds (e.g., chloronitrobenzenes) and synthetic musk fragrances (nitro musks, polycyclic musks).
Semi-permeable membrane devices (SPMDs)
These trioleine-filled polyethylene hoses are assumed to simulate the natural bioconcentration process. They are exposed to water over
a certain period of time and thus provide time-averaged concentrations. They have been applied in our group to the determination of polycyclic musks from river and pond water.
Determination has been
carried out in most cases by gas chromatography after a suitable clean-up (fractionation on silica, alox or reversed phases; gel permeation chromatography) and derivatisation where necessary. Detection has been achieved
by phosphorus-nitrogen sensitive detectors (PNDs), electron-capture detectors (ECDs) and mass spectrometers (MS).