1061-9348/01/5605- $25.00 © 2001 åAIK “Nauka /Interperiodica” 0417 Journal of Analytical Chemistry, Vol. 56, No. 5, 2001, pp. 417–420. Translated from Zhurnal Analiticheskoi Khimii, Vol. 56, No. 5, 2001, pp. 475–478. Original Russian Text Copyright © 2001 by Yaman. INTRODUCTION A knowledge of chemical forms of elements is essential for estimating their biological availability, physicochemical properties, reactivity, and element transport in the environment and in the food chain. The importance of iron in nutrition has been recognized for a long time, therefore, it has been added to certain foods. Almost all instances of Fe deficiency in plants are considered to occur because of soil factors that gov- ern Fe solubility. In green plants, iron is considered the key metal in energy transformations needed for synthe- ses and other life processes of the cells [1]. Fe defi- ciency affects several physiological processes and therefore retards plant growth and plant yield. The defi- ciency of iron is a major worldwide problem with many crops since a large number of cultivated soils are low in available content [2]. Iron and manganese compounds are greatly involved in the behavior of some macronutrients and of many trace elements. In general, Fe and Mn are interre- lated in their metabolic functions, and their appropriate proportion. The appropriate content of Fe in plants is essential both for the health of the plant and for the nutrient supply to man and animals. Important sources of iron in foods of plant origin are green leafy materi- als, most leguminous plants, and seed coats. The speciation of iron in soil is more important for estimating its uptake by plants and the food chain because the transferred Fe amount to these matrices depends on the chemical form of iron, not only on its total amount in soil. The general approach for the soil speciation studies has been to separate the soil into dif- ferent chemical reagents or solvents fractions and, by analyzing each fraction, to determine the amount of element combined or associated with each soil fraction or phase [3]. A number of extractants, including ethyl- enediaminetetraacetic acid (EDTA), diethylenetri- amine pentaacetic acid (DTPA), acetic acid, ammo- nium acetate, calcium chloride and NH 2 OH. HCl have been tested to identify metal species as exchangeable, carbonate-bound, Fe and Mn oxide-bound, organically bound, and to estimating the plant available trace met- als [4–5]. Flame atomic absorption spectrometry (FAAS) has been proved to be reliable, convenient and rapid method for analysis of toxic and nutritional metals in food, biological and environmental matrices, as a direct technique or, particularly, in combination with precon- centration method [6–15]. In this study, Fe concentrations in the fruit and soil samples were determined by using FAAS. Soil samples were dissolved by using various extractants such as the mixture of HNO 3 /H 2 O 2 , oxalic acid, Na 2 EDTA, acetic acid and citric acid. So, the relation between the fruit iron contents and the soil extractants-Fe contents was investigated. In addition, the possible chemical forms of Fe in soil were evaluated. EXPERIMENTAL Apparatus and reagents. An ATI UNICAM 929 Model flame atomic absorption spectrophotometer (AAS) equipped with an ATI UNICAM Hollow cath- ode lamp was used for the determinations. The opti- mum conditions for FAAS are given in Table 1. Unless stated otherwise, all chemicals used were of analytical-reagent grade. Throughout all analytical work, doubly distilled water was used. All glass appa- ratus have been kept permanently full of 1 M nitric acid when not in use. In the digestion and extraction proce- dures, concentrated nitric acid (65%, Merck), hydrogen peroxide (35%, Merck), oxalic acid (Merck), citric acid (Merck), ethylenediaminetetraacetic acid disodium salt (Na 2 EDTA, Merck) and acetic acid (96%, Merck) were Speciation of Iron in Soils and the Relation with Its Concentration in Fruits M. Yaman Firat University, Sciences and Arts Faculty, Department of Chemistry, Elazig, Turkey Received June 6, 2000 Abstract—An attempt was made to identify the iron species that is most responsible for plant-available Fe. Iron concentrations in fruit samples were determined by using flame atomic absorption spectrometry (FAAS). The soil samples related to these fruits were also analyzed for Fe by using various digestion and extraction reagents. The relation between the fruit-Fe and soil-extractable-Fe concentrations was examined to explain the Fe uptake of fruit from soil. The probable chemical forms of Fe in the soil were evaluated for the speci- ation of Fe. ARTICLES