Validation of a Method for Determining Heavy Metals in Some Ethiopian Spices By Dry Ashing Using Atomic Absorption Spectroscopy

The optimal conditions for determination of Pb, Cd and Cr in spices sample by FAAS after dry mineralization 1g spice samples for 5hr in a temperature of 500 °C followed dissolution in 4 mL HNO3 in Fenugreek, Black cumin, garlic and ginger. Working linear ranges are given: for Cd, 0 -6mg/l, for Cr, 0.2-1mg/l and for Pb, 2-20μg/l. Found detection limits are 0.2mg/l, 0.13mg/l and 0.02μg/l for Cd, Cr and Pb, respectively. The result obtained Lead in Fenugreek, Black cumin, garlic and ginger ranged from 0.0126 to 0.0155, 0.0205 to 0.0254, 0.0046 to 0.0066 and 0.0161 to 0.0178 mg/kg respectively. Cadmium is detected only in Fenugreek in the ranged of ND to 0.0175mg/kg where as Chromium in Fenugreek, Black cumin, Garlic and Ginger ranges from 0.0187 to 0.0219, 0.0134 to 0.0152, 0.0014 to 0.0016 and 0.0258 to 0.0346 mg/kg respectively which is under the values recommended for concentration levels present in the analyzed samples.