Determination of Zinc, Copper, Iron, Nickel, Chromium, Cadmium and Lead in Milk Samples by Flame and Electrothermal Atomic Absorption Spectrometers

Milk samples consumed in the World, contain mostly important nutrients as well as toxic elements. Quality control is necessary in the production and processing of milk samples. Also, transportation and storage conditions have effects on the composition of samples. In this study, the concentrations of zinc, iron, chromium, nickel, copper, cadmium and lead in fourteen different brands of milk samples (pasteurized and long life) purchased from markets of Turkey in Ankara were determined and evaluated by using flame and electrothermal atomic absorption spectrometers (FAAS, ETAAS). Graphite furnace heating program for Cd and Pb determinations in samples was optimized in the absence or presence of nickel (Ni) matrix modifier. The limits of detection (LOD) for Cd and Pb determined by electrothermal atomic absorption spectrometry (ETAAS) in the presence of Ni matrix modifier were 1.2 and 1.5 µg L-1, respectively. The LODs of Cu, Fe, Zn, Cr and Ni determined by flame atomic absorption spectrometry were 18.4, 71.2, 20.8, 2.1 and 2.3 µg L-1, respectively. The mean concentrations and standard deviations (±s) of Zn, Ni, Cu, Cr, Fe, Cd and Pb were 1.7 ± 0.4 mg kg-1, 0.24 ± 0.08 mg kg-1, 0.8 ± 0.2 mg kg-1, 0.8 ± 0.6 mg kg-1, 1.9 ± 0.6 mg kg-1, 46 ±5 µg kg-1 and 28 ± 3 µg kg-1, respectively found in fourteen different milk samples. The contents of elements found in samples were compared with permissible limits recommended in the health criteria by the World Health Organization (WHO) and literature values. It was concluded that the tools and materials used in milk production were not caused to heavy metal contamination. The metal concentrations in the milk samples were within the limits of the maximum permissible metal values given by WHO/FAO, the other regulations and the Turkish Food Codex.