Atomic Absorption Spectrometric methods (AAS) developed for the direct determination of Ca and Mg using flame-AAS technique have linear ranges of 0.1-2.0 μg/ml and 0.025-0.4 μg/ml with thorium concentrations optimized at 2.5 and 0.5 mg/ml, respectively, while the analytical range obtained for Sb using electrothermal-AAS technique is 0.002-0.1 μg/ml with Th sample aliquot of 2.5 mg/ml. The precision of determinations for both the techniques as evaluated from analyses of synthetic samples is 5% RSD or better. Probable mechanism for atom formation for Sb has been discussed in detail. In addition, role of chemical modifiers in enhancing the analyte signal has also been discussed.