Chemcatcher
Encyclopedia
Chemcatcher® is a passive sampling device currently being used throughout the world to measure time-weighted average (TWA) concentrations of organic and heavy metal pollutants in water. 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
.
The sampler comprises a low-cost, three component, water-tight PTFE body into which the appropriate 47 mm 3M
Empore™ receiving phase disk (e.g. C18
, styrene-divinylbenzene
, chelating resin
) is inserted depending on the class of pollutants being measured. The disk can be covered with a thin diffusion limiting membrane (e.g. low-density polyethylene, polyethersulphone
) depending on the application the device is being used for. 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®, 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/
University of Portsmouth
The University of Portsmouth is a university in Portsmouth, Hampshire, England. The University was ranked 60th out of 122 in The Sunday Times University Guide...
, together with colleagues from Chalmers University of Technology, Sweden
Chalmers University of Technology
Chalmers University of Technology , is a Swedish university located in Gothenburg that focuses on research and education in technology, natural science and architecture.-History:...
. The device is patented in a number of countries and the name is a registered trademark in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
.
The sampler comprises a low-cost, three component, water-tight PTFE body into which the appropriate 47 mm 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
Empore™ receiving phase disk (e.g. C18
C18
C18 may refer to:* a Chrysler Buccaneer - a 18 foot long daysailer* HMS C18, a submarine* Sauber C18, a Formula One racing car* Caldwell 18 , a dwarf spheroidal galaxy of the Local Group in the constellation Cassiopeiaand also :...
, styrene-divinylbenzene
Divinylbenzene
Divinylbenzene consists of a benzene ring bonded to two vinyl groups. It is related to styrene by the addition of a second vinyl group. Divinylbenzene, as it is usually encountered, is a 2:1 mixture of m- and p-divinylbenzene, containing also the corresponding ethylvinylbenzene isomers. It is...
, chelating resin
Chelating resin
Chelating resins also known as specific exchangers or chelating sorbents are usually perceived as a subgroup of ion exchange resins.Chelating resins were developed to obtain higher selectivies of at least one particular counter-ion species...
) is inserted depending on the class of pollutants being measured. The disk can be covered with a thin diffusion limiting membrane (e.g. low-density polyethylene, polyethersulphone
Polysulfone
Polysulfone describes a family of thermoplastic polymers. These polymers are known for their toughness and stability at high temperatures. They contain the subunit aryl-SO2-aryl, the defining feature of which is the sulfone group. Polysulfones were introduced in 1965 by Union Carbide...
) depending on the application the device is being used for. 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®, have a number of advantages over the use of spot or bottle sampling for monitoring pollutants in the aquatic environment
Environmental monitoring
Environmental monitoring describes the processes and activities that need to take place to characterise and monitor the quality of the 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
Water framework directive
The Water Framework Directive is a European Union directive which commits European Union member states to achieve good qualitative and quantitative status of all water bodies The Water Framework Directive (more formally the Directive 2000/60/EC of the European Parliament and of the Council of 23...
and Marine Strategy Framework Directive. An ISO standard
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
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/
External links
- http://www.port.ac.uk/departments/academic/biology/research/marinesciences/aquaticenvironmentalchemistry/ Environmental chemistry and water monitoring group, University of Portsmouth