Adsorptive determination of copper(II) in solution as its N,N-diethyldithiocarbamate on an electrode-separated piezoelectric quartz crystal

Copper(II) in solution reacts with N,N-diethyldithiocarbamate (DDTC) to form a precipitate that adsorbs on the quartz plate in an electrode-separated piezoelectric quartz crystal (PQC) assembly. The frequency change was proportional to the concentration of copper(II) in the solution over the range 0.3–5.0 μM. The adsorption depends on the pH, concentration of the buffer, standing time, concentration of DDTC, length of the mixing tube, and the flow rate of the solutions. Silver and mercury(II) alone, among many metal ions in a 5 mM EDTA solution, interfered because these metal ions reacted with DDTC to form adsorbing precipitates.