Direct determination of manganese in sea-water by electrothermal atomic absorption spectrometry with sodium hydroxide as chemical modifier for interference removal

Abstract

A direct method was developed for the determination of Mn in sea-water by atomic absorption spectrometry (AAS) with a graphite furnace. The use of NaOH for chemical modification allowed the removal of the matrix major elements by prior ashing at a lower temperature (1400 °C) for at least 100 s. Manganese was subsequently volatilized at 2000 °C and determined by AAS. The proposed method was used for the direct determination of Mn in open ocean water by the calibration technique and the standard-additions method. CASS-2 reference sea-water was used for quality control; the results were in good agreement with the certified values. By using 80 µl injections, a detection limit of 0.051 ng ml^–1 was achieved.