Proceedings

Since late 2007, the presence of the molluscide metaldehyde has been determined at significant
levels in raw surface waters in certain parts of the country. Due to the properties of this
compound, removal in water treatment processes has proved difficult and low-levels have been
determined in potable water, above the prescribed concentration of 0.1 µg/l.

STL were the first environmental testing company in the UK to setup a robust analytical method
to enable routine monitoring of this pesticide. This paper describes the development of the
analytical procedure and validation leading to UKAS accreditation. Also, how inter-laboratory
comparisons and cooperation between STL and stakeholders has been useful in demonstrating
the validity of analytical data. Consideration is also given in relation to potential interfering
compounds and the behaviour of this substance in the environment.

KEY WORDS: Analytical, determination, environment, metaldehyde, molluscide, potable, raw, water.