Detection and analysis of neonicotinoids in river waters – Development of a passive sampler for three commonly used insecticides

• A multi-residue analytical method for neonicotinoids in water was developed.
• Limits of quantitation were in the range 0.6–1.0 ng for all compounds.
• Residues of five compounds were found in a survey around Sydney.
• SDB-RPS Empore disks can be used for passive sampling of neonicotinoid residues.
• Uptake of three neonicotinoids on the SDB-RPS disks was linear for 21 d.

Increasing and widespread use of neonicotinoid insecticides all over the world, together with their environmental persistence mean that surface and ground waters need to be monitored regularly for their residues. However, current multi-residue analytical methods for waters are inadequate for trace residue analysis of these compounds, while passive sampling devices are unavailable. A new method using UltraPerformance Liquid Chromatography provided good separation of the five most common neonicotinoid compounds, with limits of quantitation in the range 0.6–1.0 ng. The method was tested in a survey of rivers around Sydney (Australia), where 93% of samples contained two or more neonicotinoids in the range 0.06–4.5 μg L−1. Styrenedivinylbenzene-reverse phase sulfonated Empore™ disks were selected as the best matrix for use in passive samplers. Uptake of clothianidin, imidacloprid and thiacloprid in a flow-through laboratory system for 3 weeks was linear and proportional to their water concentrations over the range 1–10 μg L−1. Sampling rates of 8–15 mL d−1 were correlated to the hydrophobicity of the individual compounds. The passive samplers and analytical methods presented here can detect trace concentrations of neonicotinoids in water.