Talanta 76 (2008) 1212–1217 Contents lists available at ScienceDirect Talanta journal homepage: www.elsevier.com/locate/talanta Application of a wool column for flow injection online preconcentration of inorganic mercury(II) and methyl mercury species prior to atomic fluorescence measurement V. N ¨ uket Tirtom, S ¸ ahande Goulding, Emur Henden ∗ Department of Chemistry, Faculty of Science, Ege University, Bornova, Izmir, Turkey article info Article history: Received 11 December 2007 Received in revised form 15 May 2008 Accepted 21 May 2008 Available online 3 June 2008 Keywords: Mercury Methyl mercury Preconcentration Wool Atomic fluorescence spectrometry Flow injection abstract The use of an unmodified native sheep wool packed minicolumn for the online preconcentration of Hg(II) and methyl mercury species prior to the determination of mercury by atomic fluorescence spectrome- try was investigated. Experimental conditions, such as pH, desorbing agents, volume of solution were optimized. 0.5M thioglycolic acid was found to be a successful eluting agent for both mercury species. Breakthrough and total capacities were determined. The method is simple and rapidly applicable for the determination of Hg(II) and methyl mercury in tap water. The accuracy of the method was examined by the analysis of a peach leaves standard reference material. Recoveries of spiked mercury species in tap water were 105.8% for Hg(II) and 98.8% for methyl mercury. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Mercury is one of the most toxic elements and its toxi- city to human has been well established. The environmental behaviour of mercury is interesting and differs from those of other toxic elements. Both inorganic and organic mercury compounds (i.e. methylmercury chloride [MeHg(I)], ethylmercury chloride, dimethylmercury and phenylmercury chloride) are toxic sub- stances. MeHg(I) is the most toxic mercury species [1]. Various analytical techniques have been used for the determination of mer- cury at low concentrations, but the most commonly used ones are the cold-vapour technique coupled with atomic absorption (CV-AAS) [2,3], atomic fluorescence(CV-AFS) [4,5] and inductively coupled plasma emission (CV-ICP-AES) [6,7] spectrofotometry and inductively coupled plasma mass spectrometry (ICP-MS) [8]. Although, CV-AAS is the most used technique in the determina- tion of traces of mercury, atomic fluorescence spectrometry (AFS) allows a more sensitive determination of mercury than AAS [5]. Several authors have applied flow injection analysis (FIA) methodology to the determination of mercury using the cold- vapour technique in order to combine a high analysis rate with ∗ Corresponding author. Fax: +90 232 3888264. E-mail address: emur.henden@ege.edu.tr (E. Henden). both sensitivity and selectivity of the method itself [9]. FIA systems allow inexpensive automation of chemical analysis [10]. Moreover, it works in a closed system with a significant reduction of airborne contamination and a fairly high sampling frequency [6]. Since the toxicities and the behaviour of inorganic and organic mercury species are different and all are highly toxic, determina- tion of each species of mercury at trace level is of great importance. Preconcentration techiques are usually required in order to deter- mine such low levels of mercury. Several online preconcentration methods have been reported. These include liquid–liquid [2] and liquid–solid [11] extraction processes which have been performed in the presence of various complexing agents. This is usually carried out with FIA of mercury using a minicolumn. Solid phase extraction has several advantages over other techniques such as; it is rapid, reproducible, high preconcentration factors can be attained and it requires only small volumes of solvents [12,13]. The typical sor- bents are obtained by immobilization of suitable organic agents through physical or chemical binding to different solid surfaces such as organic polymeric resins [3,6,12,14–18], inorganic silica gel [19,20] and modified silica C18 [11,21]. The capabilities of three solid chelating reagents; 7-(4-ethyl-1-methyloctyl)-8-hydroxiquinoline (Kelex 100) adsorbed on Bondapack C18 (Kelex-100/C18), 8- hydroxiquinoline immobilized on vinyl co-polymer Toyopearl gel and the commercial polystyrene/DVB ion exchange resin with paired iminodiacetate groups (Chelex-100) were compared for the 0039-9140/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2008.05.038