QUINOLINE-2-ALDEHYDE-2-QUINOLYLHYDRAZONE A SELECTIVE AND SENSITIVE COPPER REAGENT

Quinoline-2-aldehyde-2-quinolylhydrazone (QAQH) allows a simple and rapid direct determination of less than 1 p.p.m. of copper. The red 2:1 (QAQH) to copper complex has a molecular extinction coefficient in benzene of 5.8 104 at the absorption maximum of 540 nm. Most metals (up to 500 μg) do not interfere in the determination of 35 μg of copper. Equivalent amounts of cobalt and twice as much nickel can be present; 15- to 20-fold excesses of these metals are allowable in acetone: water solutions and 0.01 μg, of copper is detectable in this medium. Very small amounts of copper (1 p.p.b.) can be recovered from large sample volumes and determined directly. © 1969.