Talanta 82 (2010) 668–674 Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta Detection of s-triazine pesticides in natural waters by modified large-volume direct injection HPLC David J. Beale a,c,1 , Sarit L. Kaserzon a , Nichola A. Porter a,c,∗ , Felicity A. Roddick b,c , Peter D. Carpenter a a School of Applied Sciences, RMIT University, GPO Box 2476, Melbourne 3001, Australia b School of Civil, Chemical and Environmental Engineering, RMIT University, GPO Box 2476, Melbourne 3001, Australia c Water Quality Research Australia (Formally the CRC for Water Quality and Treatment), Private Mail Bag 3, Salisbury, South Australia 5108, Australia article info Article history: Received 26 February 2010 Received in revised form 12 May 2010 Accepted 12 May 2010 Available online 21 May 2010 Keywords: Atrazine Direct injection HPLC Large-volume injection Monolithic column Hexazinone Natural organic matter Natural waters Simazine abstract There is a need for simple and inexpensive methods to quantify potentially harmful persistent pesticides often found in our water-ways and water distribution systems. This paper presents a simple, relatively inexpensive method for the detection of a group of commonly used pesticides (atrazine, simazine and hex- azinone) in natural waters using large-volume direct injection high performance liquid chromatography (HPLC) utilizing a monolithic column and a single wavelength ultraviolet–visible light (UV–vis) detector. The best results for this system were obtained with a mobile phase made up of acetonitrile and water in a 30:70 ratio, a flow rate of 2.0 mL min -1 , and a detector wavelength of 230 nm. Using this method, we achieved retention times of less than three minutes, and detection limits of 5.7 gL -1 for atrazine, 4.7 gL -1 for simazine and 4.0 gL -1 for hexazinone. The performance of this method was validated with an inter-laboratory trial against a National Association of Testing Authorities (NATA) accredited liquid chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) method commonly used in commercial laboratories. © 2010 Elsevier B.V. All rights reserved. 1. Introduction It is common practice for water utilities to apply a risk approach to pesticide residue monitoring in drinking water catchments, where pesticides are identified and the risk of contamination is calculated (i.e., solubility and mobility of pesticide being applied in conjunction with the proximity and rate of application) [1]. This information is used to inform the water utility’s monitor- ing programme. Current Australian drinking water guidelines do not enforce a sampling program frequency (although it is recom- mended to sample for pesticide residues monthly), nor do they specify which pesticides are to be monitored, as no single method of analysis is suitable for all the organic compounds that may be present in water. Each compound, or perhaps group of com- pounds, has specific analytical requirements, so monitoring for all of them would be extremely costly, time consuming, and probably unjustified [2]. To highlight the deficiencies in current monitor- ing programs, Benotti et al. [3] investigated pharmaceutical and ∗ Corresponding author at: School of Applied Sciences (Applied Chemistry), RMIT, University, GPO Box 2476, Melbourne 3001, Australia Tel.: +61 3 9925 1787; fax: +61 3 9639 1321. E-mail address: nichola.porter@rmit.edu.au (N.A. Porter). 1 Present address: CSIRO Land and Water, PO Box 56, Highett 3190, Australia. endocrine disrupting compounds (including atrazine) in drinking water from the USA. Their study concluded that the level of ter- tiary treatment currently applied by 19 water utilities resulted in atrazine and other potentially harmful chemicals passing through to finished drinking water, and in some instances at concentrations as high as 0.9 gL -1 (note current US EPA drinking water guidelines for atrazine are set at 3 gL -1 [4]). Of greater concern was the pres- ence of atrazine in waters in areas where this compound was not believed to be in use [3]. While current standard methods recommended for the deter- mination of pesticide residues are satisfactory with respect to detection limits and analytical performance, they are often crit- icized for the time and costs involved. The development of new cost effective and rapid methodologies is becoming increasingly desirable because they enable water utilities to increase the fre- quency of sampling and broaden the range of pesticides analysed, giving them a better picture of the state of contamination in their system. As such, many researchers are looking for new techniques that address this time and cost problem, and to achieve this, some are considering enhancement and further development of liquid chromatographic techniques, in particular HPLC, ultra performance liquid chromatography (UPLC) and LC as shown in Table 1. LC–MS methods offer significant reductions in detection lim- its, and considerable effort has been expended to reduce retention times by employing fast short narrow bore columns and high 0039-9140/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2010.05.030