The effect of leached Ca2+ ion from the coral skeleton on the Fe analysis in the sea sediment using the optimized microwave BCR and Tessier methods

We determined the interferences of Ca2+ ions on Fe analysis in the sea sediment. The leached Ca from the coral skeleton affect the Fe ions to reduce the accuracy and precision of Fe analysis in sea sediment using flame-atomic absorption spectrophotometry. The Fe from sediment was leached by the optimized microwave BCR and Tessier methods. The Ca2+ ions (200, 500, 800 ppm) were added in the sediment fraction and then Fe concentrations were determined by FAAS. The results showed that Ca2+ ions interferences of Fe in all sediment fractions using BCR and Tessier methods. The interference of Ca2+ ions in the optimized microwave BCR method released the higher Fe concentrations. The addition of Ca2+ ions with concentrations of 200, 500, and 800 ppm in the optimized microwave BCR and Tessier methods obtained total concentrations of Fe 3737, 3700, 3658 mg/kg, and 1775, 1809, 1815 mg/kg, respectively. The presence of Ca formed the refractory oxy compounds due to the reaction between oxygen gas and Ca atoms in the air-acetylene flame of the FAAS flame. This suggested the interferences Ca reduce the accuracy in determining Fe concentration in the detector of FAAS.