Abstract: | Abstract The sulfate ion is extracted into toluene with nonionic surfactant span 20 and crystal violet. A linear calibration curve was obtained between the absorbance due to crystal violet in the extract and sulfate concentrations over the range 2.5 × 10?5 to 2.5 × 10?4 mol 1?1 (2.4 to 24 ppm) in the aqueous phase. |