Wikipedia
Chemcatcher is a highly versatile and cost-effective passive sampling device for monitoring a wide variety of pollutants in water. Most monitoring programmes involve the periodic collection of low volume spot samples (bottle or grab) of water, which is challenging, particularly where levels fluctuate over time and when chemicals are only present at trace, yet toxicologically relevant concentrations. The Chemcatcher passive sampling device is currently being used throughout the world to measure time-weighted average (TWA) or equilibrium concentrations of a wide range of pollutants in water. This allows the end user to obtain a more representative picture of the chemicals that may be present in the aquatic environment. The Chemcatcher concept was developed by Professors Richard Greenwood and Graham Mills at the University of Portsmouth, together with colleagues from Chalmers University of Technology, Sweden. The device is patented in a number of countries and the name is a registered trademark in the United Kingdom.
Chemcatcher® comprises a robust, reusable three-component a low-cost, three component, water-tight PTFE body. Two different designs are available to accommodate different types of commercially available 47 mm diameter receiving phase disks:
- 3M Empore Chemcatcher: weighs 83 g and houses the 47 mm 3M Empore range of receiving phases (e.g. C18, SDB, chelating, anion and cation exchange and RAD disks) . As well as the appropriate Empore receiving disk, you will need a diffusion-limiting membrane to prepare the device for deployment.
- Horizon Atlantic Chemcatcher: weighs 130 g and houses the 47 mm Horizon Atlantic SPE disks as receiving phases (e.g. HLB, C18 and DVB). As well as the appropriate Atlantic receiving disk, you will need a diffusion-limiting membrane to prepare the device for deployment.
The use of quality-controlled, commercially available receiving phases allow high reproducibility as compared to some other passive sampling devices. The bound receiving phase also ensures that the active sampling area of the device remains constant during laboratory or field calibration uptake experiments and in field deployments. By altering the combination of receiving phase and diffusion-limiting membrane (low-density polyethylene, polyethersulphone or cellulose acetate), you can monitor potable, surface , coastal and marine environment. The sampler can be deployed in the field for extended periods of time ranging from days to weeks. The specific pollutants of interest are sequestered by the samplers and these are retained on the receiving phase disk. After retrieval from the environment the pollutants are eluted from the disk and analysed in the laboratory using conventional instrumental methods. In order to obtain TWA concentrations the sampler must first be calibrated in the laboratory so as to ascertain the uptake rate (usually measured as the volume of water cleared per unit time i.e. L/h for the analyte) of the pollutant of interest. The Chemcatcher® has been used in a range of aquatic environments; however, most work to date has been in monitoring the TWA concentrations of priority and emerging pollutants surface waters.
The use of passive sampling devices, such as the Chemcatcher®, and the polar organic chemical integrative sampler (POCIS), have a number of advantages over the use of spot or bottle sampling for monitoring pollutants in the aquatic environment. The latter technique gives only an instantaneous concentration of the pollutant as the specific time of sampling. Passive samplers, depending on their mode of use can give either the TWA or equilibrium concentration of the pollutant over the deployment period. The measurement of TWA concentrations give a better indication of the long-term environmental conditions and enables improved risk assessment. Such devices have potential roles in monitoring programmes such as those underpinning the European Union’s Water Framework Directive and Marine Strategy Framework Directive. An ISO standard concerning the use of passive samplers for the determination of priority pollutants in surface waters is available for end users of this technology.
More information on the Chemcatcher® passive sampling device and ongoing research activities can be found at http://www.port.ac.uk/research/chemcatcher/