Current Analytical Chemistry, 2012, 8, 543-549 543 Determination of Trace Amounts of Cr(III) in Water Samples by Flame Atomic Absorption Spectrometry Gulsin Arslan* Selcuk University, Science Faculty, Department of Chemistry, Konya 42075, Turkey Abstract: A fast and effective microextraction technique is proposed for the determination of trace amounts of Cr(III) in water samples, using ultrasound-assisted emulsification-microextraction (USAEME) followed by flame atomic absorption spectrometry (FAAS). In the proposed approach, sodium diethyldithiocarbamate trihydrate solution (NaDDTC.3H 2 O) was used as a chelating agent and chloroform was selected as extraction solvent. After determination of the most suitable sol- vent and extraction time, some effective parameters such as an extraction solvent volume, temperature, and pH were in- vestigated and optimized. The optimized USAEME procedure used 100 L of chloroform, 20 min of extraction with no ionic strength adjustment at 50 ºC and 5 min of centrifugation at 4000 rpm. The method was applied to the analysis of tap, well, dam on industrial waste water samples and the Trace Metals in Drinking Water standards CRM-TMDV. The detec- tion limit for Cr(III) was 0.079 g L 1 with an enrichment factor of 95, and the relative standard deviation was 2.8-1.1% (n=8, c=500 g L 1 ). The proposed USAEME procedure has been demonstrated to be viable, simple, rapid and easy to use for the residue analysis separation of Cr(III). Keywords: Ultrasound assisted emulsification microextraction, Determination, Atomic absorption spectrometry, Chromium (III). 1. INTRODUCTION Chromium is used in a variety of industrial applications [1–3]. Chromium is mainly stable in the two oxidation states of Cr(III) and Cr(VI) [4,5]. Cr(VI) is known as more toxic, mutagenic and carcinogenic than Cr(III) [6]. The guideline for drinking water prescribed by the World Health Organiza- tion for Cr(VI) is 0.05 mg L -1 [7]. Large quantities of chro- mium are discharged into the environment. Therefore, the analysis and determination of trace amounts of chromium in environmental samples should be continued by developing analytical methods. In order to determine chromium species in various sam- ples, different analytical techniques such as flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma optical emission spectrometry (ICP OES), induc- tively coupled plasma mass spectrometry (ICP-MS), anodic stripping voltammeter, ion chromatography and UV–vis spectrometer have been reported [8-14]. From the analytical tools listed above, FAAS is widely used because of its low costs, operational facility and high sample throughput [8]. Direct determination of metal ions at trace levels by FAAS is limited not only due to insufficient sensitivity, but also to matrix interference. In order to determine trace levels of chromium, a separation and enrichment step prior to their determinations may be beneficial [15]. Thus, preconcentra- tion and separation steps are needed prior to the determina- *Address correspondence to this author at the Selcuk University, Science Faculty, Department of Chemistry, Konya 42075, Turkey; Tel: +90 332 2233852, Fax: + 90 332 2412499; E-mail: 71arslan@gmail.com tion by FAAS. For the speciation of chromium, the separa- tion methods reported in the literature are usually based on liquid–liquid extraction (LLE) [16,17], solid phase extraction (SPE) [18,19], coprecipitation [20], and ion chromatography [21], etc. Separation and preconcentration based on cloud point extraction (CPE) are becoming an important and prac- tical application of surfactants in analytical chemistry [22]. However, LLE, as the oldest preconcentration and separation technique in analytical chemistry [23], is time-consuming and requires large amounts of organic solvents [24]. Com- pared with LLE, SPE offers simpler operation, a higher en- richment factor, and ease of automation, but the amounts of elution solvents are still relatively large [15,25,26,27]. In the past few years, a novel liquid–liquid microextrac- tion system, termed as liquid-phase microextraction (LPME) or solvent microextraction (SME), was developed [28, 29]. Up to now, several different LPME modes have been devel- oped, such as single drop-microextraction (SDME) [30,31], hollow fiber LPME [32], headspace LPME [33] and dynamic LPME [34]. Microextraction techniques are fast, simple, inexpensive, environmentally friendly and compatible with many analytical instruments [24, 35]. Nevertheless, some drawbacks, such as instability of the droplet and relatively low precision are often reported [36]. It is well known that ultrasound is a powerful aid in the acceleration of various steps, such as homogenizing, emul- sion forming, and mass transferring between immiscible phases, in the processes of separation and extraction [37]. Ultrasound-assisted liquid–liquid extraction and ultrasound- assisted emulsification extraction have been successfully used as an alternative to LLE, which can attain extraction equilibrium in a short time [38–40]. The implosion bubble 1 - /12 $58.00+.00 © 2012 Bentham Science Publishers