Spectrophotometric method for determination of germanium in foods with newcolor reagent trimethoxylphenylfluorone

A high sensitive and selective spectrophotometric method for determination of germanium has been developed. The method is based on the reaction of ger manium with a new reagent trimethoxylphenylfluorone (TMPF) in the presence of Triton X-100. The absorbency of the complex (lambda (max) = 505 nm) incr eases linearly with concentration up to 0.24 mug ml(-1) germanium in aqueou s solution with a relative standard deviation (R.S.D.) of 1.02%. The molar absorptivity of the germanium complex, the limit of quantification and limi t of detection were found to be 1.7 x 10(5) l mol(-1) cm(-1), 0.70 and 0.21 ng ml(-1), respectively. The influences of metal ions on the determination of germanium were investigated; all foreign ions studied, could be tolerat ed in considerable amounts, 50 mg of Ca and Mg, 100 mg of Fe and AL 60 mg o f Ni, 8 mg of Mn and 1.0 mg of Pb do not interfere with the determination o f 1.0 mug of germanium, so the selectivity is superior to published methods , especially, with regards to Ti, Zr, Sn, Mo and W, which always interfere with the determination of germanium in other methods. The color reaction sy stem is simple and stable. The reaction of germanium with TMPF is complete within 30 min and the absorbency of the complex remains almost constant for at least 24 h in a phosphoric acid medium. In addition, the synthesis of t rimethoxylphenylfluorone and the preconcentration of low germanium concentr ations were also investigated in detail. The proposed method has been appli ed to determine traces of germanium in foods with satisfactory results. (C) 2001 Elsevier Science B.V. All rights reserved.