Determination of beryllium as the acetylacetone complex

Discussion. Beryllium forms an acetylacetone complex, which is soluble in chloroform, and yields an absorption maximum at 295 nm. The excess of acetylacetone in the chloroform solution may be removed by rapid washing with O.lM-sodium hydroxide solution. It is advisable to treat the solution containing up to 10 g of Be with up to 10 mL of 2 per cent EDTA solution the latter will mask up to 1 mg of Fe, Al, Cr, Zn, Cu, Pb, Ag, Ce, and U. 

Procedure. Prepare a solution containing 10 jug of beryllium in 50 mL. (CARE Beryllium compounds are toxic.) Use beryllium sulphate, BeS04,4H20. To 

0 mL of this solution contained in a beaker, add dilute hydrochloric acid until the pH is 1.0, and then introduce 10.0 mL of 2 per cent EDTA solution. Adjust the pH to 7 by the addition of 0.1M sodium hydroxide solution. Add 

0 mL of 1 per cent aqueous acetylacetone and readjust the pH to 7-8. After standing for 5 minutes, extract the colourless beryllium complex with three 10 mL portions of chloroform. Wash the chloroform extract rapidly with two 50 mL portions of 0.1M sodium hydroxide in order to remove the excess of acetylacetone. To determine the absorbance at 295 nm (in the ultraviolet region of the spectrum) it may be necessary to dilute the extract with chloroform. Measure the absorbance using 1.0 cm absorption cells against a blank. 

Repeat the determination with a solution containing 100 jig of iron(III) and of aluminium ion the absorbance is unaffected. 

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