4-Ethyl-1-(pyridin-2-yl)thiosemicarbazide (HEPTS) has been used as a new complexing agent in cloud point extraction (CPE)
for preconcentration and determination of trace amounts of copper in saturated saline medium. The chemical variables affecting
the separation and determination processes were optimized. Copper(II) is preconcentrated using 0.05% (w/v) Triton X-114 and
10−4 M HEPTS at pH 6. The surfactant rich phase containing the complex was dissolved in 2 mL MeOH and determined spectrophotometrically.
The calibration curve is linear in the 0.1–25 ng/mL copper range. The proposed method was applied successfully in the determination
of copper in water and saturated saline samples. The reaction between CuSO4 and HEPTS yields a deep-blue solid complex which is characterized by analytical and spectroscopic analyses.