Multi-element determination of Cu, Fe, Ni and Zn content in vegetable oils samples by high-resolution continuum source atomic absorption spectrometry and microemulsion sample preparation

Abstract

The aim of this work was to evaluate the microemulsification as sample preparation procedure for determination of Cu, Fe, Ni and Zn in vegetable oils samples by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). Microemulsions were prepared by mixing samples with propan-1-ol and aqueous acid solution, which allowed the use of inorganic aqueous standards for the calibration. To a sample mass of 0.5g, 100μL of hydrochloric acid and propan-1-ol were added and the resulting mixture diluted to a final volume of 10mL. The sample was manually shaken resulting in a visually homogeneous system. The main lines were selected for all studied metals and the detection limits (3σ, n=10) were 0.12, 0.62, 0.58 and 0.12mgkg(-1) for Cu, Fe, Ni and Zn, respectively. The relative standard deviation (RSD) ranged from 5% to 11 % in samples spiked with 0.25 and 1.5μgmL(-1) of each metal, respectively. Recoveries varied from 89% to 102%. The proposed method was applied to the determination of Cu, Fe, Ni and Zn in soybean, olive and sunflower oils.

Evaluation of cadmium, lead, copper, iron and zinc in Turkish dietary vegetable oils and olives using electrothermal and flame atomic absorption spectrometry

“…While iron and copper are regulated as criteria for the qualities of edible olive oils and olives, lead and cadmium are considered as real pollutants reported in legislations and literature (IOOC, 2003, Bakkali et al, 2009Economic European Communities, 2006). Cu, Fe and Zn are important for human health as essential nutrients having different biological functions in all living organisms such as increasing oil oxidation, while Cd and Pb are very important for humans due to their toxicities and metabolic roles even at low concentrations (Mendil et al, 2009;Zhu et al, 2011;Ansari et al, 2009;Guldas, 2008;Nunes et al, 2011;Sardans et al, 2010). The sources of Cd, Cu, Pb, Fe and Zn contamination in these samples might come from the soil as natural metal sources, manufacturing, packaging process and environmental pollution (Mendil et al, 2009;Zeiner et al, 2005;Benincasa et al, 2007).…”

“…Among these techniques, ETAAS and FAAS are extensively employed for the determination of the total trace element contents in samples because of their high sensitivities, lower detection limits and low costs (Mendil et al, 2009;Sardans et al, 2010;Nunes et al, 2011). However, in general, the determination of metals in oil samples by atomic spectrometric methods is highly difficult due to high background signals obtained from organic contents of the sample matrix and the volatilization of analytes together with organic compounds (Angioni et al, 2006;Sahan et al, 2007;Souza et al, 2008;Nunes et al, 2011). Some sample pretreatment methods such as extraction, pre-concentration and dilution are required to minimize the organic matrices in vegetable oils before using a spectroscopic technique.…”

“…In some cases, these methods are tedious and time consuming with the consequent risk of sample contamination, analyte loss and an incomplete dissolution of the sample matrix (Carrilho et al, 2002;Ansari et al, 2009). Microwave digestion systems, used for laboratory applications, offer enormous advantages in dissolving the samples (Angioni et al, 2006;Sahan et al, 2007;Souza et al, 2008;Ansari et al, 2009;Nunes et al, 2011). Platform atomization, matrix modification, integrated absorbance and powerful background correction techniques together with ETAAS have been used to overcome these problems.…”

Metal Determinations in Olive Oil

“…On the other hand, oil sample can be diluted in a suitable solvent or emulsified with an appropriate emulsifier in a rapid pretreatment for direct determinations. The atomic spectrometers are the most commonly used devices but have some problems such as the reduced stability of the analytes in the solution, requirement of organometallic standards, the use of dangerous organic solvents or sample digestion with an acid or acid mixture (Nunes et al, 2011).…”

“…The analytical techniques used for metal determinations in oils are both emission and absorption spectrophotometry. ICP-OES (Allen et al, 1998;Angioni et al, 2006 ;Anthedimis et al, 2005;Costa et al, 2001;De Souza et al, 2005;Murillo et al, 1999;Zeiner et al, 2005), FAAS (Batı & Cesur, 2002;Carbonell et al, 1991;Köse Baran & Bağdat Yaşar, 2010;Nunes et al, 2011), ETA-AAS (Karadjova et al, 1998;Kowalewska et al, 1999 ;Zeiner et al, 2005), GFAAS (Allen et al,1998 ;Ansari et al, 2009;Calapaj et al, 1988;Chen et al, 1999;Cindric et al, 2007;De Leonardis et al, 2000;Hendrikse et al, 1988Hendrikse et al, , 1991Lacoste et al, 1999;Martin-Polvillo et al, 1994 ;Matos Reyes & Campos, 2006;Mendil et al, 2009;Nash et al, 1983;Van Dalen, 1996), and ICP-MS (Benincasa et al, 2007 ;Bettinelli et al, 1995;Llorent-Martinez et al, 2011a, 2011bPereira et al, 2010;Wondimu et al, 2000) are the most commonly used techniques for the determination of metal contents in oils (Duyck et al, 2007).…”