Determination of Selected Essential and Non-Essential Metals in Three Types of Teff (Eragrostis tef) Cultivated in Southern Ethiopia

Abstract

Teff (Eragrostis tef) is used to supply staple food “injera” for many Ethiopians. The present study was aimed toward determining the extent of selected metals that can exist in three types of teff cultivated in selected districts of southern Ethiopia. The level of those metals was determined by flame atomic absorption spectrometry. The optimized wet digestion procedure was evaluated employing a spiking method and an acceptable percentage recovery of (91.1% - 108.9%) has been obtained for metals in the teff. Oven dried 1 g of teff samples were digested using 5 mL of HNO3 and 1 mL of HClO4 at 300°C for 3 hours. The result indicated that the mean concentration of metals (in mg/kg dry weight basis) in teff samples were found to be from 1206.9 to 1768.9 of Ca, 2463.9 to 2554.7 of Mg, 82.6 to 109.9 of Na, 2879 to 3075 of K, 207.4 to 239.5 of Fe, 55.9 to 100.4 of Mn, 27.1 to 87.1 of Zn, 5.4 to 45.5 of Cu and 0.118 to 0.130 of Pb respectively. However, Cd is below the method detection limit. A statistical analysis of variance revealed that there was a significant difference (p ≤ 0.05) between the mineral content in three teff types and teff from the three districts. Red teff had higher essential metal contents except Cu followed by brown teff. Strong positive correlation was recognized between Mg with Ca and K, the rest have moderate or weak correlation. Further study has been done on the mineral contents of similar variety or three types of teff with the soil analysis from different locations.