[Determination of trace germanium in coal by spectrophotometry with 2,4-dichlorophenylfluorone]

A method for the determination of germanium in coal samples by spectrophotometry has been developed. The color reaction of germanium with 2,4-dichlorophenylfluorone (2,4-DCIPF) in the presence of cetyltrimethylammonium bromide (CTMAB) has been studied. The results show that Ge(IV) reacts on 2,4-DCIPF and CTMAB to form a multicomponent complex in a 1.8-2.5 mol x L(-1) H2SO4 medium. The complex has the maximum absorption wavelength at 516 nm and its apparent molar absorptivity epsilon is 1.38 x 10(5) L x mol(-1) x cm(-1). Beer's law is obeyed in the range of 0-12.5 microg x (25 mL)(-1) for Ge(IV). The recovery of standard addition is 103%-106% and the relative standard deviation (RSD) is 1.1%-1.7%. This method has been applied to the determination of Ge(IV) in coal samples with satisfactory results.