Development and Validation of Analytical Method for Estimation of Calcium in Herbomineral Formulation by Atomic Absorption Spectrophotometry

Calcium determination is normally done by conventional titrimetric methods (complexometric titration). In this study, a simple, precise, accurate, rapid and sensitive method has been developed for calcium (Ca) determination in Maxcal-C Tablet (herbo-mineral formulation) and its raw materials by Atomic Absorption Spectrophotometer (AAS). For complete digestion of the sample, closed vessel wet digestion technique was used with 69% HNO3 and 30% H2O2 (7:1) as digestive solvents. Analysis was performed on AAS (AA-6300) at λmax 422.7 nm. Calcium nitrate Ca(NO3)2 was used as a standard for Calcium and the linearity of the standard was excellent over a concentration range of 0.5 to 20 μgmL-1. The regression coefficient (r2) was 0.999. For intraday and interday precision % RSD was obtained between 0.48%-1.95% and 3.48%-5.01%, respectively which complied with the standard range for AAS. Recovery was achieved at 93.24%, 99.73%, 101.75% for 3 levels of spikes (80%, 100%, 120%) respectively, which complied with the standard range 75- 125% for AAS. However, the AAS method produced accurate and reproducible results and also overcame the colour and other ions interference, which are common problems with the titrimetric method. The results of both techniques (the AAS method and the titrimetric method) were compared, which showed good estimation by AAS.