Journal of Radioanalytical and Nuclear Chemistry, Vol. 262, No. 1 (2004) 287293 02365731/2004/USD 20.00 AkadØmiai Kiad, Budapest ' 2004 AkadØmiai Kiad, Budapest Kluwer Academic Publishers, Dordrecht Sources of trace elements in total diet: A statistical approach N. K. Aras, 1 A. Chatt 2 1 University of Bahcesehir, 34538 Istanbul, Turkey 2 Department of Chemistry, Dalhoise University, Halifax, NS, B3H 4J3, Canada (Received October 10, 2003) We have collected sixteen total diet samples from two socioeconomic groups in Turkey by duplicate portion techniques. Samples were homogenized with titanium-blade homogenizer, freeze dried and analyzed for their minor and trace elements mostly by neutron activation analysis. Bread and flour samples were also collected from the same regions and analyzed similarly by instrumental neutron activation analysis. We have determined concentrations of more than 25 elements in total diets, bread and flour, and fiber and phytate in total diets. We have determined daily dietary intakes of these population groups, probable source of elements through correlation coefficients, and enrichment factor calculations. Introduction Food normally supplies the major proportion of the total daily trace element intake by humans. Because of the important functions of trace elements, they must be taken in such an amount that is necessary for the maintenance of the life and vital functions of the body. 1 At present, twenty-six of the ninety naturally occurring elements appear to be essential to life. These consist of eleven major and micro minerals, which are in g/kg, or mg/kg levels in tissues. The other fourteen elements, As, Cr, Co, Cu, F, I, Fe, Mn, Mo, Ni, Si, Sn, V, and Zn, which are called essential trace elements, are in mg/kg or g/kg levels. Since the main source of these elements for humans is total diet, their studies in staple foods and their daily intake are very important. 2 In the last decades, many countries and international organizations like the FAO, WHO and IAEA have shown an increasing interest on the concentrations of trace elements in food and diet and have started programs in order to monitor the trace element content of them. 3 Wheat is by far the most used staple food in Turkey. Estimates show that about 400 g wheat or wheat products are used daily by the average Turkish people and much of it in the form of bread. 4 In this work we will present trace element data for total diet, bread and flour measured by instrumental neutron activation analysis, INAA and AAS, and relations among trace elements. Experimental Collection of diet, bread and flour samples Diet samples were collected from Turkish individuals considering parameters such as socio- economical, cultural and regional variations. Details of these studies were given elsewhere. 2 Sampling is the most critical phase of the entire analytical itinerary. Any factor affecting the sample collection can be a source of error, which cannot be eliminated at a later stage. There are a number of different methods of collection of diet samples. One of them is the preparation of meals in the laboratory by considering the eating habits of the selected region. The second procedure is the duplicate portion technique. 5 In this technique, diet samples were collected for three consecutive days from each subject. A duplicate portion of everything a subject had consumed during a 3-day period was collected. This included all the meals and drinks. The inedible parts, skin of fruits, seeds, bones, etc., were not collected, as the subjects did not eat these parts. The samples were collected from persons at the Middle East Technical University (METU) and at a village near Ankara, Lalahan (LAL). The METU subjects could be assumed to belong to the middle upper economic class, and LAL to the rural economic class. Since total diet consists of the various food items such as fats, and vegetables, it must be homogenized with great care before analysis. The samples were homogenized with a homogenizer having titanium blades and freeze dried. 2 Information about the sampled individuals and dry weight of daily intake is listed for METU and LAL samples in Table 1. Bread and flour samples were collected in 1995 with the help of Ankara Bakeries Associations. 6 We selected six major bakeries in Ankara and collected the most consumed white bread and flour samples. In each case, we collected three fresh breads, placed in clean polyethylene bags. We dried them for eight hours at 50 C then powdered them with a homogenizer, which had titanium blades.