Cloud point extraction (CPE) has been used for the simultaneous pre-concentration of cadmium, copper, lead and zinc
after the formation of a complex with 1-(2-thiazolylazo)-2-naphthol (TAN), and later analysis by flame atomic absorption
spectrometry (FAAS) using octylphenoxypolyethoxyethanol (Triton X-114) as surfactant.