Author's personal copy Detection and analysis of neonicotinoids in river waters – Development of a passive sampler for three commonly used insecticides Francisco Sánchez-Bayo a,⇑ , Ross V. Hyne b a University of Technology Sydney, PO Box 123 Broadway, NSW 2007, Australia b Centre for Ecotoxicology, Office of Environment & Heritage NSW, PO Box 29, Lidcombe, NSW 1825, Australia highlights  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. article info Article history: Received 3 July 2013 Received in revised form 17 October 2013 Accepted 19 October 2013 Available online 2 December 2013 Keywords: Analytical method Passive sampling Trace residues Monitoring abstract Increasing and widespread use of neonicotinoid insecticides all over the world, together with their envi- ronmental persistence mean that surface and ground waters need to be monitored regularly for their res- idues. 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 Ultra- Performance 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 riv- ers around Sydney (Australia), where 93% of samples contained two or more neonicotinoids in the range 0.06–4.5 lgL 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 lgL 1 . Sampling rates of 8–15 mL d 1 were correlated to the hydrophobicity of the indi- vidual compounds. The passive samplers and analytical methods presented here can detect trace concen- trations of neonicotinoids in water. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction In the last decade, neonicotinoid insecticides have been the fastest growing class of insecticides in modern crop protection (Jeschke and Nauen, 2008). Thus, in 2008 neonicotinoids com- prised 24% of the insecticide market in Europe, equal to organo- phosphorus and carbamates combined, and 80% of the insecticidal seed treatments (Jeschke et al., 2011). The reasons for this success are threefold: (i) their selectivity and extreme efficacy in treating arthropod pests; (ii) their low fish and mammalian toxicity; and (iii) their versatility in application methods. Indeed, neonicotinoid insecticides act agonistically on the arthropod’s nicotinic acetylcholine receptors (nAChRs), and are extremely toxic to aquatic insects and their larvae, with re- ported acute LC50s in the lgL 1 range (Beketov and Liess, 2008; Stoughton et al., 2008; Roessink et al., 2013). In general they are very toxic to all aquatic arthropods except waterfleas – see Hayasaka et al., 2012b. However, due to structural differences in the polypeptide subunit containing the neonicotinoid-binding re- gion of the vertebrates’ nAChRs, neonicotinoids pose a relatively low risk to fish and mammals (Tomizawa and Casida, 2003). Above all, it is their versatility in application methods that have led to their wide global usage. Because of their solubility in water, all neonicotinoids are systemic insecticides and are applied as seed dressings in preference to foliar sprays (Sánchez-Bayo et al., 2013b). In this way application costs from aerial and ground-rig sprays are reduced, avoiding also risk of human exposure among farmers. For all the above, neonicotinoids are widely used in 0045-6535/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2013.10.051 ⇑ Corresponding author. Address: Centre for Ecotoxicology, University of Tech- nology Sydney, c/Lidcombe, NSW 2141, Australia. Tel.: +61 29995 5091; fax: +61 29995 5183. E-mail addresses: sanchezbayo@mac.com (F. Sánchez-Bayo), Ross.Hyne@ environment.nsw.gov.au (R.V. Hyne). Chemosphere 99 (2014) 143–151 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere