Evaluation of measurement uncertainty components associated with the results of complexometric determination of calcium in ceramic raw materials using EDTA

Calcium is an important constituent of mineral like calcite, dolomite, gypsum and bio-ceramic raw material like hydroxyapatite. Those are frequently used for the manufacture of cement, mortar, glass, synthetic ceramic bone supplement, dental enamel, etc. Determination of exact quantity of calcium in those materials is therefore very essential. The calcium content has been determined complexometrically in a ceramic raw material at pH 12, using di-sodium salt of EDTA. The major sources of uncertainty of the results of measurement are contributions from repeatability, standardization of EDTA, volume measurement by volumetric flask, burette, pipette and end point detection. Sources of uncertainty have been identified and combined by following the EURACHEM guidelines. The results show that the major sources of uncertainty arise from standardization, repeatability of the experiment and end point detection by burette. Cause–effect diagram has been drawn to explain the uncertainty budget.