Spectrophotometric determination of trace amounts of germanium in minerals and ores with 9-(o-chlorophenyl)-2,6,7-trihydroxyxanthen-3-one in the presence of cetyltrimethylammonium bromide

Abstract

A simple, highly sensitive and selective spectrophotometric method has been developed for the determination of germanium in a strongly acid medium (1.2 M H₂SO₄+ 3 M H₃PO₄) using 9-(o-chlorophenyl)-2,6,7-trihydroxyxanthen-3-one (o-chlorophenylfluorone, o-Cl-PF) in the presence of cetyltrimethylammonium bromide. The germanium complex exhibits an absorption maximum at 516 nm, and has a molar absorptivity of 1.82 × 10⁵ l mol^–1 cm^–1. Beer's law is obeyed in the range 0–0.20 µg ml^–1 of germanium, and the method is relatively free from interference from other metal ions. The method can be used to determine micro-amounts of germanium in minerals and ores without the isolation of germanium tetrachloride.