In this study, a new solid-phase extraction procedure has been developed for preconcentration and determination of Co ions in different water samples by flame atomic absorption spectrometry (FAAS). Cobalt was preconcentrated as N,N 0 -bis(pyridine-2-ylmethyl)benzene-1,4-diamine (Co-BPMBDA) from sample solutions using a column containing Amberlite XAD-7 and was determined. In order to achieve the best performance for the method, effects of several parameters such as pH, concentrations of ligand, sample flow rate, eluent, and matrix ions on the method efficiency were investigated. Under optimum conditions, the preconcentration factor was found to be 200 for 1000 mL waters samples. Detection limit based on the 3S b criterion was calculated as 0.24 mg/L for 100 mL of sample solution and relative standard deviation was found to be 1.8%. The method was applied to determine the trace amounts of cobalt in water samples.Keywords: Amberlite XAD-7; Cobalt; Preconcentration; FAAS; Solid-phase extraction
IntroductionCobalt is an important element for industry and for biological systems. Cobalt is present in vitamin B 12 and is an essential micronutrient for all living systems [1]. Drinking water, food, and inhalation are common ways of cobalt contamination for living organisms. The deficiency of cobalt in human and animal bodies results in anemia [2], while large amounts of cobalt causes to toxic effects (mechanism to fail in asthma, kidney and liver disorders, heart growth and expansion, sinus tachycardia), usually after occupational exposure to cobalt dust (cobalturia, cobaltemia) [3, 4]. There are two main alternative sources of cobalt for aquatic environment: Natural sources and anthropogenic sources. The natural sources include volcanic emissions, the weathering of rocks by the action of water and decomposition of plant waste. The main human-related sources of cobalt to aquatic environment are sewage and industrial waste [5].Since one of the routes of incorporation of cobalt into the human body is by ingestion, its determination in drinking water, food, and environmental samples such as soil and dust becomes very important [6].Several analytical techniques including electrothermal atomic absorption spectrometry (ETAAS) [7], inductively coupled plasma optical emission spectrometry (ICP-OES) [8], inductively coupled plasma mass spectrometry (ICP-MS) [9], flame atomic absorption spectrometry (FAAS) [10], and high performance liquid chromatography (HPLC) [11,12] have been devised for the determination of cobalt in different matrixes.Due to the high complexity of the matrixes and the low level of cobalt ions in the aquatic samples, separation, and preconcentration step prior to cobalt analysis are needed [13,14]. There are many methods for preconcentration such as, coprecipitation, solvent extraction, electrochemical deposition, membrane extraction, and solid-phase extraction [15][16][17]. Solid-phase extraction (SPE) has become a preferred method at enrichment of many metal ions prior to their analysis by FAAS and other tec...
