Analytical Services

Analytical Services lab

What we do

Natural Resources Wales Analytical Services (NRWAS) is an analytical laboratory accredited by the United Kingdom Accreditation Service (UKAS), with industry-leading expertise in complex freshwater and sediment analysis.

Originally founded in 1979 in Llanelli as Welsh Water Authority’s South West District Laboratory, and later hosting the Research & Development facility for the Environment Agency’s National Laboratory Service, we have been providing expert analytical solutions for over 40 years. Collectively our team has over 500 years of analytical experience.

As an integral part of NRW we help deliver the Welsh Government’s statutory obligations to the European Union’s Water Framework, Bathing Water and Habitats Directives.

We process a wide range of fresh water, saline and bathing water samples, as well as sediment, soils and biota, taken across Wales to help ensure our Welsh waters achieve environmental quality standards which promote benefits for wildlife and the people of Wales.

Our standards and accreditation

We are accredited to an international industry standard – ISO/IEC 17025:2017 by the UKAS, the national accreditation body for the United Kingdom.

The laboratory is externally audited on an annual basis carried out in accordance with our stringent Quality Management System requirements. 

See our UKAS Schedule of Accreditation.

Analytical services​​


Our organics lab offers tests on aqueous samples which cover contaminants such as herbicides, pesticides, and other organic compounds. This includes:

  • Polycyclic Aromatic Hydrocarbons (PAHs)
  • Polychlorinated biphenyls (PCBs)
  • Phenols
  • Synthetic Pyrethroids
  • Volatile Organic Compounds (VOCs)

These compounds are found in substances such as oil, coal, coolant fluids, disinfectants and insecticides. If the composition of an aqueous sample is unknown, or if a variety of compounds are of interest, we offer qualitative screening tests which covers a range of compounds.

Screening tests

We offer Liquid Chromatography Mass Spectrometry (LCMS) and Gas Chromatography Mass Spectrometry (GCMS) screens to identify the presence or absence of compounds within the Hazardous Chemicals Database, as well as our database of over 1600 compounds which includes pharmaceuticals and their metabolites, pesticides, illicit drugs and other compounds of toxicological concern.

If you have any uncertainty about what analyses are best suited for your interests, our team of technical specialists can advise on an approach most appropriate for your requirements.

Find out more about the literature our analysts have contributed to in the development of organic methods.


Our inorganics lab analyse fresh and saline water samples for various minerals and compounds naturally occurring in watercourses such as nitrates, phosphates and sulphates along with testing for other water quality characteristics such as pH, turbidity and colour.

Our team can test for low levels of nutrients occurring naturally in watercourses, or for high levels often present from sewage and trade outlets. The analyses performed by our Inorganics team assist in the development of river basin management plans by characterising the chemical pressures facing the aquatic environment in each of Wales's three river basin districts.


Our metals lab can perform analyses which detect trace levels of metals and minerals in biota, sediment, soils and aqueous samples. The testing capabilities of the metals lab covers both naturally-occurring elements such as calcium, magnesium or aluminium, as well as hazardous heavy metals such as mercury, cadmium and lead.

Aqueous samples are analysed for trace metals using Inductively Coupled Plasma Mass Spectrometry (ICPMS) or Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES). Aqueous mercury is quantified by Cold Vapour Atomic Fluorescence.

In addition to the quantification of trace metals, our metals lab is fully trained in performing comprehensive particle size analysis, quantification of organic carbon and % dry solids.


Each summer, our microbiology team tests samples from 105 bathing waters across Wales to ensure the public are protected from the health risks caused by potential sewage outflows from farmland, waste management works and populated areas.

Our microbiology lab tests for two specific type of bacteria, E coli and Intestinal enterococci, which give an indication of the level of faecal pollution. Both indicator organisms can affect human health by causing stomach upsets and enteric disorders if ingested.

Passive sampling

We offer an industry-leading passive sampling service, supervised by the technical specialists who helped develop and perfect this technique. Passive sampling provides a more comprehensive method of characterising watercourses, as the sampling device is left in-situ for typically 2 to 6 weeks, allowing us to capture episodic events or low concentrations more likely to be missed by traditional spot samples.

Passive samplers accumulate dissolved contaminants and analysis can be used to calculate a time weighted concentration of various pollutants such as pesticides, industrial chemicals, metals and some nutrients.

This form of sampling and analysis is ideal for monitoring purposes if concentrations in spot samples are suspected to be below standard limits of detection, due to the integrative accumulation of contaminants in the samplers.

We offer the following passive samplers:

  • Chemcatchers™
  • Silicone Rubber Membrane Samplers
  • Diffusive Gradient in Thin Film (DGT) samplers

Chemcatchers are suitable for the quantitative detection of polar organic compounds such as acid herbicides, molluscicides, neonicitinoid pesticides, and the qualitative detection of veterinary medicines, pharmaceuticals and organophosphate pesticides.

Silicone Rubber Membrane Samplers are suitable for the qualitative detection of non-polar organics including PAHs, PCBs, organochloride pesticides and synthetic pyrethroids.

Diffusive Gradient in Thin Film (DGT) samplers are suitable for detection of certain metals (cadmium, copper, manganese, nickel, lead, zinc) and phosphate.

Find out more about the literature our analysts have contributed to in the development of passive sampling techniques.

Water quality sondes

NRWAS offers a range of Water Quality instrumentation, including sondes and handheld meters which can be deployed to measure and automatically transmit a range of parameters in freshwater and marine environments. We maintain a purpose-built laboratory and workshop which offers calibration and maintenance services for sondes and handheld meters.

A sonde can be set to take measurements at regular pre-set time intervals (e.g. every 15 minutes) to collect continuous readings of water quality indicators following deployment. Our sondes can be deployed for up to 3 months of continuous logging, depending on the model and environmental conditions in which it is deployed.

The use of a sonde often presents a more cost-effective and efficient solution in comparison to a prolonged programme of routine sampling which may miss the effects of events such as storms, tidal cycles, or pollution incidents on water quality.

The following water quality indicators can be measured via a sonde:

  • Conductivity
  • Temperature
  • Depth or Vented Level
  • Dissolved Oxygen
  • Flourescent Dissolved Organic Matter (fDOM)
  • pH
  • Oxidation Reduction Potential (ORP)
  • TAL-Chlorophyll (Total Algal)
  • TAL Phycocyanin or TAL-Phycoerythrin
  • Turbidity

Additional parameters such as ammonia, salinity or total suspended solids may also be calculated using one or more of the parameters above.

Drinking water standards

We are unable to advise regarding the safety of any source of water for human consumption.

Our aqueous testing services are not accredited against drinking water quality standards.

Our contribution to literature


Cole, R. F., Mills, G. A., Bakir, A., Townsend, I., Gravell, A. & Fones, G. R. 2016. A simple, low cost GC/MS method for the sub-nanogram per litre measurement of organotins in coastal water. MethodsX, 3, 490-6.

Schumacher, M., Castle, G., Gravell, A., Mills, G. A. & Fones, G. R. 2016. An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry. MethodsX, 3, 188-94.

Passive sampling

Rimayi, C., Chimuka, L., Gravell, A., Fones, G. R. 2019. Use of the Chemcatcher Passive Sampler and Time-of-Flight Mass Spectrometry to Screen for Emerging Pollutants in River sin Gauteng Province of South Africa. 2019. Environ Monit Asses, 191:388.

Castle, G. D., Mills, G. A., Gravell. A., Leggat, A., Stubbs, J., Davis, R., Fones, G. R. 2019. Comparison of Different Monitoring Methods for the Measurement of Metaldehyde in Surface Waters. Environ Monit Assess, 191:75.

Townsend, I., Jones, L., Broom, M., Gravell, A., Schumacher, M., Fones, G. R. 2018. Calibration and Application of the Chemcatcher® Passive Sampler for Monitoring Acidic Herbicides in the River Exe, UK Catchment. Environ Sci Pollut Res, 25, 25130-25142.

Castle, G. D., Mills, G. A., Bakir, A., Gravell, A., Schumacher, M., Townsend, I., Jones, L., Greenwood, R., Knott, S., Fones, G. R. 2017. Calibration and Field Evaluation of the Chemcatcher® Passive Sampler for Monitoring Metaldehyde in Surface Water. Talanta, 179, 57-63.

Petrie, B., Gravell, A., Mills, G. A., Youdan, J., Barden, R. & Kasprzyk-Hordern, B. 2016. In Situ Calibration of a New Chemcatcher Configuration for the Determination of Polar Organic Micropollutants in Wastewater Effluent. Environ Sci Technol, 50, 9469-78.

Vrana, B., Smedes, F., Prokeš, R., Loos, R., Mazzella, N., Miege, C., Budzinski, H., Vermeirssen, E., Ocelka, T., Gravell, A. & Kaserzon, S. 2016. An interlaboratory study on passive sampling of emerging water pollutants. TrAC Trends in Analytical Chemistry, 76, 153-165.

Mills, G. A., Gravell, A., Vrana, B., Harman, C., Budzinski, H., Mazzella, N. & Ocelka, T. 2014. Measurement of environmental pollutants using passive sampling devices - an updated commentary on the current state of the art. Environ Sci Process Impacts.

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