Flow Injection Determination of Calcium and Magnesium in Soluble Pharmaceutical Tablets by Flame Atomic Absorption Spectrometry Using Ultrasound for Sample Preparation

A simple and rapid continuous manifold for sample dissolution based on ultrasound energy is evaluated for flow injection determination of calcium and magnesium in pharmaceutical tablets by flame atomic absorption spectrometry. Several parameters that could influence the dissolution process were evaluated by Plackett-Burman experimental designs. The obtained results showed that samples were easily dissolved with ultrapure water at room temperature at a flow-rate of 6 mL min(-1) under the action of ultrasound energy during 30 seconds. The analytical method was characterized and the limit of detection and limit of quantification for the two metals were 2.8 and 9.5 mg g(-1) for Ca and 7.5 and 25 mu g g(-1) for Mg, respectively. The sampling frequency of the system was about 50 samples per hour, with repeatability, expressed as relative standard deviation, in the range 0.5 and 3.0% for both metals. The proposed methodology was successfully applied to determine calcium and magnesium in multivitamin tablets.