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Abstract

Aqueous two-phase system formed by mixing (NH4)2SO4 and tetrabutylammonium bromide (TBAB) has been applied to the gentle separation of trisodium salt of copper (II) chlorophyllin (CuCL–Na). An aqueous two-phase system was obtained as follows: to a 3.0 mL of 1.0 mol/L TBAB aqueous solution, 1.0 mL of CuCL–Na aqueous solution containing less than 0.30 mg of CuCL–Na, 1.0 mL of pH 8 buffer solution and 1.1 g of (NH4)2SO4 were added and the mixture was shaken for 1 min, then left at room temperature for 3 h. A 0.5 mL portion of the top phase was diluted to 10 mL with water and its absorbance was then measured at 405 nm against a reagent blank similarly prepared. The CuCL–Na can be quantitatively extracted into the TBAB-rich upper phase at the wide pH range. It was considered that the extractable species was an ion pair complex of the type CuCL–TBA.