Analysis of a mixture using the internal normalisation method

Sample. The solvent extraction of aluminium from aqueous solution using acetylacetone can provide a suitable sample solution for gas chromatographic analysis. 

Take 5mL of a solution containing about 15 mg of aluminium and adjust the pH to between 4 and 6. Equilibrate the solution for 10 minutes with two successive 5 mL portions of a solution made up of equal volumes of acetylacetone (pure, redistilled) and chloroform. Combine the organic extracts. Fluoride ion causes serious interference to the extraction and must be previously removed. 

Introduce a 0.30 pL portion of the solvent extract into the gas chromatograph. It is found that solutions of concentrations greater than 0.3 M are unsuitable as they deposit solid and thus cause a blockage of the 1 jj.L microsyringe used for the injection of the sample. The syringe is flushed several times with the sample solution, filled with the sample to the required volume, excess liquid wiped from the tip of the needle and the sample injected into the chromatograph. 

Apparatus. A gas chromatograph equipped with a flame-ionisation detector and data-handling system. The use of a digital integrator is particularly convenient for quantitative determinations, but other methods of measuring peak area may be used (Section 9.4). 

Pure nitrogen (oxygen-free), at a flow rate of 40 mL min is used as carrier gas. The dimensions of the glass column are 1.6 m length and 6 mm o.d., and it is packed with 5 per cent by weight SE-30 on Chromosorb W as the stationary phase. The column is maintained at a temperature of 165 °C. 

---

ANALYSIS OF A MIXTURE USING THE INTERNAL NORMALISATION METHOD 9.7... 

---