Method Validation for the Determination of the Concentration of Metals in Teff Samples
Abstract: The validity of the method was assured by spiking the samples with a standard solution of known concentration of the target analytes. The calibration curves were prepared from standards of known concentration. Five working standards were used for the calibration curves corresponding to 0, 5, 10, 15 and 20 mg/L for Ca, Cu, Fe, Pb, Mn, Cd and Zn; 0, 1, 2, 3 and 4 mg/L for Al concentration levels. All the working standards of metals solution used for calibration curve exhibited very good linearity with squared regression coefficients (R2) values ranged from 0.9990 to 0.9999.The regression equations for each of the metals were plotted and were best fit equations. In all the cases, the regression coefficients (R2) were found to be in the acceptable linear range. The method detection limits were low enough (≤ 0.56 mg/kg) to detect the concentrations of the metals in the samples at a trace levels using microwave plasma atomic emission spectroscopy. From the stock solution of 1000 ppm, 119.5 µL of Fe, 43.5 µL of Ca and 15.3 µL of Zn were added to 0.5 g of teff sample. For Cu an intermediate standard solution of 100 ppm was prepared and 30 µL of Cu was added to 0.5 g of teff sample. For Pb and Cd intermediate standard solutions of 10 ppm were prepared and 63 µL of Pb and 45 µL of Cd were added to 0.5 g of teff sample. The spiked and non-spiked samples were digested and analyzed in similar condition using the optimized procedure. Six metals were analyzed in triplicate standard metal solutions to evaluate the efficiency of the method and the percentage recoveries lies within the range from 92 to 104%, and were in the acceptable range of 100 ± 10%.
Keywords: Detection Limits: Metals: Method Validation: Recovery: Spiking: Ethiopia
