such as inductively coupled plasma atomic emission spectrometry (ICP-AES) [2,4,5], inductively coupled plasma mass spectrometry (ICP-MS) [6], flame atomic absorption spectrometry (FAAS) [7,8], adsorptive stripping square wave voltammetry (Ad-SSWV) [9] and derivative potentiometric stripping analyses (dPSA) [10,11]. Most of these detection techniques require sample pretreatments involving the addition of one or more organic reagents, extraction with acids or acidic mixtures, wet digestion or dry ashing for eliminating the matrix effect. These sample pretreatment procedures are time consuming, prone to contamination and involve potential risks such as analyte losses, impoverishment of the overall LOD as a result of dilution of sample and the use of dangerous acid or acid mixtures. Neutron activation analysis (NAA) [12] and graphite furnace atomic absorption spectrometry (GFAAS) [3,5] has been used to analyze edible oils requiring no sample preparation. However, such expensive instrumentation is not commonly available.There have been many reports about Schiff bases and related complexes for the determination of certain metals in biological, clinical, nutritional, environmental and industrial samples [13][14][15][16][17][18][19][20][21]. In the present work, a new method was improved for the determination of Fe(III) and Cu(II) in edible oils without any digestion procedure. For this purpose, a new water-soluble Schiff base (Fig. 1) was synthesized, characterized [22] and utilized as a complexation reagent for the extraction of Fe(III) and Cu(II) from oil phase to aqueous phase.
Materials and Methods
Reagents and ChemicalsMerck Titrisol 109972 iron stock solution (1,000 mg iron L −1 ; FeCl 3 in 15 % HCl) (Darmstadt, Germany) andAbstract In the present work, a novel and rapid extraction method for Fe(III) and Cu(II) from liquid edible oils is described. N,N′-Bis(4-methoxysalicylidene)-1,2-diamino ethane (MSE) was utilized for the extraction of metal ions and the determination was achieved by flame atomic absorption spectrometry (FAAS). In order to optimize the extraction conditions, a central composite design (CCD) technique was employed. The optimum conditions, the ratio of MSE solution volume to oil mass, stirring time and temperature, were determined as 1.2 and 1.1 mL g −1 ; 24.0 and 31.8 min and 25.3 and 33.2 °C for Fe(III) and Cu(II) extraction, respectively. The feasibility of the improved method was tested with oil-based metal standards affording 98.6 % recovery for both metals and 67.3 ng g −1 for Fe(III) and 15.3 ng g −1 for Cu(II) as limit of detection (LOD).
