FAQ's

Q. Has this new method been published?

We recently published a full paper in Environmental Science & Technology with full details:

New device and method for flux-proportional sampling of mobile solutes in soil and groundwater. H. de Jonge and G. Rothenberg, Environ. Sci. Technol., 2005, 39, 274-282.

DOI: 10.1021/es049698x

If, for any reason, you cannot access this paper, email us - we will be happy to send you a reprint.

Q. How long can the sampler remain in place?

Typical installation times can range from 1-2 weeks up to 6 months, depending on the application. The maximum installation time is determined by the sorption capacity and tracer dissolution properties. We customize the cartridge for specific applications, and provide units with a minimum and maximum recommended installation time.

Q. Do flow and concentration dynamics affect the sampling step?

No, the inherent strength of Sorbisense equipment is the flow-proportional weighing of this variation, so that you retrieve average solute concentration regardless of flow- and concentration dynamics.

Q. What tracer compounds are used, and do they pose a threat to the environment?

We use moderate to low soluble salts that are harmless to the environment. Our product development includes a growing range of tracer compounds, and we can help you choose the one that is best suited to your analytical requirement.

Q. What is the detection limit compared to conventional liquid samples?

The detection limit will depend on the volume of water passing the sampler, which is as also true for normal liquid samples. Therefore, there is a minimum installation time that guarantees a detection limit that is the same as for conventional liquid samples. The precise detection limit can be quantified at all times from the actual volume of water that passed the sampler.

Q. Is tracer dissolution affected by the macro-chemistry of the aqueous phase?

Above a threshold concentration, tracer dissolution will be affected by ionic strength and pH. Our development work has resulted in tracer compounds that are hardly affected by ionic strength and pH normally encountered in soil solutions. But until we have developed a more complete data-base of dissolution properties, we recommend a separate calibration for each new application.

Q. How is clogging of the cartridges with colloids avoided?

The cartridges are built-up as a multi-porous system, containing large macropores (up to 0.1 mm) down to nanopores (<1-10 nm). Macropores secure capillary contact and a high hydraulic conductivity. If colloids are to be retained, it is achieved by surface reactions rather than by mechanical filtering.

Q. How do we avoid biodegradation of organic compounds in the sampler?

We use advanced adsorbents with very high sorption affinities. Adsorption occurs in nano-pores that are not bio-available to micro-organisms. We perform ageing and mass recovery studies to document the biological and analytical availability of sorbed compounds.

Q. Can a mass flux be measured?

In soil or groundwater, a direct measure of mass flux can be obtained if disturbance of the flow pattern around the sampler can be minimized. If the flow pattern around the sampler diverges or converges deliberately or non-deliberately, a flux-proportional solute concentration will be retrieved instead.

Q. How about the sampling of water that is transported through macropores in the soil?

Our samplers combine the known principle of zero-tension lysimeters. These samplers will only "see" water that is not capillary-bound in macropores, such as wormholes or cracks. Such a sampler will allow you to quantify the contribution of macropores to the leaching of solutes.