1983 Volume 32 Issue 7 Pages 429-434
A method for the determination of microgram amounts of copper, based on the extraction flotation of bathocuproine-copper (I) chelate cations, has been developed. The chelate cations in an aqueous solution (pH4.68.0) were floated with lauryl sulfate anions by bubbling nitrogen through the aqueous phase, and collected with yield of about 97% in a mixture of 4-methyl-2-pentanone and 1, 2-dichloroethane (4 : 1 in vol.) on the solution surface. The copper in the organic phase was determined by spectrophotometrically. The proposed method could be successfully applied to the determination of copper in a small quantity of serum sample. The recommended procedure is as follows. Place (0.30.5) ml of serum and 0.5ml of trichloroacetic acid (0.2g/ml) solution in a 10ml test tube. Heat the mixture for 15min at 90°C, cool to room temperature and centrifuge for 15min at 1800g. Remove the supernatant and wash the precipitated serum proteins two times with 1ml each of water. To the combined supernatant, add 1ml of ammonium citrate (0.2g/ml) solution and 2ml of hydroxylammonium sulfate (0.1g/ml) solution, adjust pH to 7.0±0.2 with 0.5M sodium hydroxide solution, then add 4.7ml of ethanol and 1ml of 0.01% bathocuproine ethanol solution. After standing for 15min, add 2 ml of 0.005% sodium lauryl sulfate solution to the solution and dilute to 20ml with water. In a flotation cell, place the solution and 1.2ml of the mixed solvent. Bubble nitrogen through the aqueous phase at a flow rate of 60ml min-1. After 7min of bubbling, remove the organic phase, make up to 1ml with ethanol and measure the absorbance at 476nm against the reagent blank with 1cm microcells. The analyzed values were in good agreement with those obtained by using the modified LandersZak's method.
