Abstract: The construction and characteristics of a thin-layer electrolytic cell with graphite glass as working electrode are presented. In the medium of NH₄Cl-NH₃H₂O, the peak current is proportional to the concentration of copper from 10^-6mol/Lto 10^-2 mol/L(1 .27 ×10^-5～1.27 ×10^-9 g Cu) at a voltage of -0.30V. The correlation coefficient is 0.99. During the determinationt the charging current and poison of mercury do not exist, and oxygen must in the solution must not be removed. The method has been applied to determination of copper in aluminium alloy and in the steel.

Key words: Thin-layer electrolytic cell, Determination of copper, Flow injection method