title: An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry.
abstract: The molluscicide metaldehyde (2,4,6,8-tetramethyl-1,3,5,7-tetraoxocanemetacetaldehyde) is an emerging pollutant. It is frequently detected in surface waters, often above the European Community Drinking Water Directive limit of 0.1 μg/L for a single pesticide. Gas chromatography mass spectrometry (GC-MS) can be used to determine metaldehyde in environmental waters, but this method requires time consuming extraction techniques prior to instrumental analysis. Use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) can overcome this problem. We describe a novel LC-MS/MS method, using a methylamine mobile phase additive, coupled with on-line sample enrichment that allows for the rapid and sensitive measurement of metaldehyde in surface water. Only the methylamine adduct of metaldehyde was formed with other unwanted alkali metal adducts and dimers being suppressed. As considerably less collision energy is required to fragment the methylamine adduct, a five-fold improvement in method sensitivity, compared to a previous method using an ammonium acetate buffer mobile phase was achieved. This new approach offers: •A validated method that meets regulatory requirements for the determination of metaldehyde in surface water.•Improved reliability of quantification over existing LC-MS/MS methods by using stable precursor ions for multiple reaction monitoring.•Low limits of quantification for tap water (4 ng/L) and river water (20 ng/L) using only 800 μL of sample; recoveries > 97%.
authors.affiliation: Natural Resources Wales, Llanelli Laboratory, 19 Penyfai Lane, Llanelli SA15 4EL, UK.
authors.forename: Melanie
authors.initials: M
authors.lastname: Schumacher
authors.affiliation: School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO1 3QL, UK.
authors.forename: Glenn
authors.initials: G
authors.lastname: Castle
authors.affiliation: Natural Resources Wales, Llanelli Laboratory, 19 Penyfai Lane, Llanelli SA15 4EL, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Gravell
authors.affiliation: School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth PO1 2DT, UK.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Mills
authors.affiliation: School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO1 3QL, UK.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Fones
keywords: An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry; Liquid chromatography–tandem mass spectrometry; Metaldehyde; Methylamine; Molluscicide; On-line enrichment; Surface water