Evaluation of atomic absorption Spectrophotometry (ashing, non-ashing) and titrimetry for calcium determination in selected foods
Three commonly used techniques, namely atomic absorption spectrophotometry (AAS-Ashing and AAS-Non Ashing) and titrimetry (potassium permanganate titration) have been evaluated in this study to determine the calcium content in six food samples whose calcium levels ranged from 0 to more than 250mg/100g sample dry matter (DM) basis. An attempt was made to evaluate these three techniques of analysis for all different levels on the basis of accuracy, precision, reproducibility of results, simplicity of operation, economy, speed, sensitivity, specificity, and safety. Results show that AAS-Ashing is the most reliable technique for calcium determination as it is most accurate and detects more calcium compared to the other two techniques. Moreover, independent of calcium levels, potassium permanganate titration proved to be the second most reliable method and determinations could be made more precisely, but it suffered from interference by other ions. AAS-Non Ashing proved to be the least accurate technique of analysis. The latter technique, however requires the shortest sample preparation procedure.
Keywords : AAS-Ashing, AAS-Non Ashing, potassium permanganate titration, calcium, food.