A simple, fast and environment-friendly cloud-point extraction (CPE) process was described for the determination of cobalt ion. The extraction of analyte involved the formation of the hydrophobic complex between cobalt ions and ammonium pyrrolidineditiocarbamate (APDC) and then its extraction into a surfactant-rich phase. 1 ml ethanol was added to the surfactant-rich phase prior to its analysis by visible spectroscopy. The variables affecting extraction efficiency, such as sample pH, volume of surfactant, volume of APDC solution, amount of NaCl, centrifugation conditions, bath temperature and time were optimized. Under the selected optimized conditions, the calibration graph using the proposed method for cobalt was linear in the range of 0.5 - 4.5 mg L-1 (r = 0.9981). The precision (RSD) was 3% (C = 1 mg L-1, n = 8). The enrichment factor was found to be 17 and the detection limit was 0.045 mg L−1. The proposed method was successfully applied to the determination of cobalt ions in real samples.
