Bis(6-methyl-2-pyridyl)glyoxal dihydrazone as a spectrophotometric reagent for the rapid determination of copper in alkalis, milk and brine

Abstract

The synthesis, characteristics and analytical applications of bis(6-methyl-2-pyridyl)glyoxal dihydrazone are described. This compound produces coloured solutions selectively with copper(I) ions (λ_max.= 440 nm, ε= 8·7 × 10³ l mol^–1 cm^–1) that can be extracted into various organic solvents; it behaves as a cuproine-type reagent. The 1:1 orange-yellow copper(I) complex has been used for the spectrophotometric determination of trace amounts of copper in saturated brine, alkalis and milk. The most important advantage of using this reagent is the total recovery of copper that is possible from ammoniacal solutions.