American Journal of Environmental Protection 2015; 4(4): 188-192 Published online July 19, 2015 (http://www.sciencepublishinggroup.com/j/ajep) doi: 10.11648/j.ajep.20150404.13 ISSN: 2328-5680 (Print); ISSN: 2328-5699 (Online) Levels of Selected Essential and Nonessential Metals in Roasted Coffee Beans of Yirgacheffe and Sidama, Ethiopia A. Tesfay Gebretsadik 1 , Tarekegn Berhanu 2 , Belete Kefarge 3 1 Department of Industrial Chemistry, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia 2 Strengthening of Agricultural Pesticide Residue Analysis System Project, JICA, Addis Ababa, Ethiopia 3 Department of Chemistry, Jigjiga University, College of Natural and Computational Science, Jigjiga, Ethiopia Email address: tgtesfageb@gmail.com (A. T. Gebretsadik) To cite this article: A. Tesfay Gebretsadik, Tarekegn Berhanu, Belete Kefarge. Levels of Selected Essential and Nonessential Metals in Roasted Coffee Beans of Yirgacheffe and Sidama, Ethiopia. American Journal of Environmental Protection. Vol. 4, No. 4, 2015, pp. 188-192. doi: 10.11648/j.ajep.20150404.13 Abstract: The study was conducted to assess the contents of essential and non-essential metals in coffee beans. For this matter, seven essential metals such as K, Mg, Ca, Na, Mn, Cu and Zn and two nonessential metals (Cd and Pb) in four roasted coffee samples (washed Yirgacheffe, unwashed Yirgacheffe, washed Sidama and unwashed Sidama) were determined by FAAS. Closed microwave assisted wet digestion method with addition of concentrated (69-70%) HNO 3 and 30% H 2 O 2 were selected for decomposition of ground roasted coffee samples. Generally, the levels of metals in all roasted coffee samples were found: K > Mg > Ca > Na >Mn> Zn > Cu, but the non-essential metals Pb and Cd were found to be below method detection limit. The digestion method was evaluated by spiking roasted coffee samples and their percentage recoveries were in the range of 95 −104 %. It is suggested that the consumption of roasted coffee beans could be a source of dietary essential metals and a possible entrance path way for trace metals to the food chain. Keywords: Essential and Non-essential Metals, FAAS, Micro-wave Digestion, Roasted Coffee Beans 1. Introduction Currently, one of the greatest challenges is the production of food, not only in sufficient amounts, but also with adequate nutritional quality, assuring nutritional balanced and a contaminant free food supply. Moreover, the increasing awareness of the important role of trace elements in biological systems has stimulated the extension and refinement of studies in this field which have provided a great deal of information. Accordingly, the content of mineral micronutrients and some other trace elements in coffee beans is of great general and special interest [1]. Over two-thirds of all the research literature on geographic origin commodities involves the analysis of vitamins or other organic molecules (amino acids, triglycerides, volatile aromatic compounds, etc.) [2]. However, a shortcoming of using vitamins (or other organic compounds) is their susceptibility to degradation those organic chemicals including enzymatic changes from the time of harvest through storage to the time of analysis [3]. This is also important because coffee beans are processed and organic chemical profiles are likely to be especially susceptible. The use of minerals and trace elements is therefore powerful because trace elements are significantly more stable in the commodity versus vitamins or some other types of organic compounds [4]. For determination of metals in raw or roasted coffees have used different analytical techniques like flame atomic absorption spectrometry (FAAS) [5], inductively coupled plasma optical emission spectrometry (ICP OES) [6] and neutron activation analysis (NAA) [7], results of these studies have revealed that the levels of metals differs among coffee species and varieties growing in the different parts of the world [8, 9]. This study aimed to determine the levels of essential and non-essential metals in washed and unwashed Yirgacheffe and Sidama roasted coffee beans which grow in Ethiopia. 2. Experimental 2.1. Instruments and Apparatus Coffee Roasting Machine (PROBAT-WERKE, BRZ-2 type