ORIGINAL PAPER Ligandless temperature-controlled ionic liquid-phase microextraction of lead(II) ion prior to its determination by FAAS Zeid A. Alothman & Erkan Yilmaz & Mohamed Habila & Azza Shabaka & Mustafa Soylak Received: 24 December 2012 / Accepted: 18 March 2013 # Springer-Verlag Wien 2013 Abstract We describe the application of temperature- controlled ionic liquid based microextraction (TC-IL-ME) of lead(II) ion. The method does not require the use of an organic solvent or a ligand. Rather, the IL is directly added to the aqueous sample containing Pb(II) in a centrifuge tube, and the mixture is heated to 80 °C for 4 min. After cooling at 0 °C, the solution turns cludy due to the formation of fine droplets of the IL containing Pb(II). The IL is separated by centrifugation, acidified, and directly submitted to FAAS by microinjection. The effects of pH value, volume of IL, extraction time, tem- perature, sample volume and matrix were optimized to result in a preconcentration factor of 30, a detection limit of 5.8 μgL -1 , and a limit of quantification of 19.3 μgL -1 . The method was validated by analyzing a certified reference ma- terial (NCSZC81002B; hair). A recovery test performed with spiked samples gave values between 102 % and 105 %. The method was also used to determine Pb(II) in hair samples. Keywords Ligandless . Microextraction . Ionic liquids . Preconcentration . Lead Introduction Lead is one of the most toxic elements and adversely affects enzymatic activity, kidney function and the tissues of humans and animals. Lead has been classified as a Group B2 (probable) human carcinogen by The U.S. Environmental Protection Agency (EPA) [1–6]. Therefore, the effective ana- lytical methods for determining and evaluating trace levels of lead in biological samples such as hair or urine is critical. Lead determinations in biological samples are difficult due to matrix effects and because the concentration of lead is lower than the detection limits of several instrumental methods. To solve these problems and obtain higher accu- racy, many preconcentration-separation methods such as liquid–liquid extraction (LLE), solid-phase extraction (SPE), coprecipitation, cloud point extraction and ion- exchange separation have been developed [7–13]. However, applications of these methods are limited by several disad- vantages; they are time-consuming, use large quantities of toxic solvents and generate secondary waste, which leads to environmental problems and complex management issues. In recent years, small-scale preconcentration-separation methods called micro extraction were very popular to elim- inate these problems [14–16]. These microextraction proce- dures are dispersive liquid-liquid microextraction (DLLME) [17], single-drop microextraction (SDME) [18] and solid- phase microextraction (SPME) [19] and others. The use of preconcentration and separation methods with ionic liquids such as single-drop microextraction (SDME) [ 20 , 21 ], cold-induced aggregation microextraction (CIAME) [22], in situ solvent formation microextraction (ISFME) [23], and dispersive liquid-liquid microextraction (DLLME) [24, 25] has increased dramatically in the last few years. Temperature-controlled ionic liquid-phase microextrac- tion ((TC-IL-ME)) is a simple, highly sensitive, low cost, efficient and powerful method to extract and measure traces of metals and organic compounds in real samples [26–28]. The aim of our work was to develop a novel temperature- controlled ionic liquid-phase microextraction (TC-IL-ME) technique coupled with FAAS with a low detection limit and high repeatability to determine Pb(II) in hair samples. The Z. A. Alothman : M. Habila Chemistry Department, College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia E. Yilmaz : M. Soylak (*) Fen Fakultesi, Department of Chemistry, Erciyes University, 38039, Kayseri, Turkey e-mail: soylak@erciyes.edu.tr A. Shabaka High Institute of Public Health, Environmental Health Department, Alexandria University, Alexandria, Egypt Microchim Acta DOI 10.1007/s00604-013-0979-6