ICP-AES determination of minor- and major elements in apples after microwave assisted digestion

The aim of this paper was to determine the content of minor and major elements in apples by inductively coupled plasma atomic emission spectrometry (ICP-AES). Prior to ICP-AES measurement, dried apples were digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of open and closed microwave system as sample preparation procedures are discussed. In whole apples, flesh and peel Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were analysed after optimisation and validating the analytical method using ICP-AES. The accuracy of the method determined by spiking experiments was very good (recoveries 88–115%) and the limits of detection of elements of interest were from 0.01 up to 14.7 μg g−1. The reference ranges determined in all apple samples are 39–47 mg g−1 for K, 9–14 mg g−1 for Na, 3–7 mg g−1 for Mg, 3–7 μg g−1 for Zn, 0.7–2.8 μg g−1 for Sr. The range of Mn in peel 4–6 μg g−1 is higher compared to whole apple from 0.7 to 1.7 μg g−1. Cd is found only in peel, in the concentration range of 0.4–1.1 μg g−1.