Determination of some traces metal levels in cheese samples packaged in plastic and tin containers by ICP-OES after dry, wet and microwave digestion.

The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Se and Zn in cheese samples packaged in plastic and tin containers were analyzed using inductively coupled plasma-optical emission spectrometry after microwave, wet and dry digestion processes. In order to evaluate the best digestion method, the relationships between the concentrations of trace metals in cheese samples after microwave digestion was compared by wet and dry ashings. Microwave digestion was found fast, reliable, simple, and excellent procedure in comparison with dry and wet ashing methods. The accuracy of the digestion procedures was determined by using standard reference material (GBW 07605-Tea). The order of levels of the elements in the white cheese samples packaged in tin containers was determined to be Cd<Co<Mn<Cr<Se<Pb<Cu<Ni<Zn, after microwave digestion and cream cheese samples in plastic containers Cd<Mn<Co<Cr<Se<Pb<Ni<Cu<Zn, respectively. There were considerable differences among of the studied element contents of cheese samples packaged in tin and plastic containers, indicating that cheese types and packaging materials play a key role in the content of trace metal.