Use of Ceramic Dosimeters in Water Monitoring

Passive sampling with Ceramic Dosimeters allows for time-integrated monitoring of dissolved chemicals in ground- and surface water. The purely diffusion controlled device is based on a porous ceramic membrane. This membrane has the shape of a tube. The ceramic tube functions as diffusion barrier and at the same time serves as container to hold a solid sorbent. The latter can be selected according to compounds of interest and time scales needed for monitoring. The sorbents are required to have a high affinity and capacity for the uptake of the chemicals of concern combined with easy extraction at high recovery rates. As long as such sorbents can be found, Ceramic Dosimeters fit any analytical need. Diffusive transport of chemicals across the ceramic membrane at steady state can be described by Fick’s first law. Thus, the accumulated mass of a chemical at the end of an exposure period can be used to calculate the average concentration at which this chemical was present over the entire sampling time. Based on this, the Ceramic Dosimeter allows for quantification of chemical concentrations over extended periods without the need for calibration or frequent snap-shot sampling. The idea of the Ceramic Dosimeter was first conceived by Grathwohl [1] and by now, a number of laboratory experiments as well as explorations in the field have proven the suitability of Ceramic Dosimeters for time-integrated, long-term monitoring. Applications so far include the sampling of polycyclic aromatic hydrocarbons (PAHs) using Amberlite IRA-743 (Sigma-Aldrich) as solid sorbent receiving phase [2-4] as well as the sampling of benzene, toluene, ethylbenzenes, and xylenes (BTEX) [5], naphthalenes [5] and chlorinated hydrocarbons (CHCs) [5, 6] using Dowex Optipore L-493 (Supelco). Furthermore, the Ceramic Dosimeter provided the basis for the development of the Toximeter, the first passive sampler that is directly compatible with toxicological tests. Biosilon polystyrene beads (Nunc) served as the sorbent material in the initial development of the Toximeter, which focused on PAH sampling and responses elicited in vertebrate cells (see also Chapter by Schirmer et al.). The goal of this Chapter is to provide details on the functioning of Ceramic Dosimeter sampling devices with particular focus on the role of the ceramic membrane and requirements regarding the solid receiving phase. Additionally, a number of practical considerations will be discussed to highlight strengths and limitations of Ceramic Dosimeters in the field.JRC.H.5-Rural, water and ecosystem resource