Chiang Mai Journal of Science

  In this study, a simultaneous cloud point (CP) and solid phase extraction (SPE) procedure for the phase separation and preconcentration of Cu(II) and Fe(III) ions using a synthesized chelating agent, 7'-amino-2,4'-dioxo-2'-thioxo-1',2',3',4'-tetrahydrospiro[indoline-3,5'-pyrano[2,3-d]pyrimidine]-6'-carbonitrile (L1), is reported. L1 is used with tert-octylphenoxypoly(ethoxyethanol) (Triton X-114), in a CPE process to concentrate the metal ions followed by adsorption on activated carbon (AC) and determination of the concentration of metal ions by flame atomic absorption spectrometry (FAAS). The main factors affecting the process, such as the concentrations of Triton X-114, and L1, AC dose as well as the pH of the sample solutions were optimized by a response surface methodology (RSM). The detection limits (3 sdb∙m⁻¹) of Cu(II) and Fe(III) ions under optimum conditions ( X1 (pH) = 6, X2 (AC dose) = 15 mg, X3 (Triton X-114 concentration) = 0.22 % (v/v), and X4 (L1 concentration) = 0.40% (w/v) ) were obtained 0.45 and 0.65 µg∙L⁻¹, respectively. The developed method, validated with certified reference materials, was successfully used in determining the concentrations of metal ions in food and water samples.