Determination of Acrylonitrile Monomer in Acidic and Alkaline Extractants

2 Determination of Acrylonitrile Monomer in Acidic and Alkaline Extractants 

Direct polarography of synthetic solutions of acrylonitrile in the 6% hydrochloric acid and in the 5 % sodium carbonate extractants is not possible as both extractants produce interfering waves in the acrylonitrile polarogram. Also, when TMAI was added to the 6% hydrochloric acid extractant, the quaternary salt decomposed and free iodine was liberated. 

The applicability of the azeotropic-distillation procedure described by Daues and Hamner [2] for separating acrylonitrile monomer from interfering impurities before polarography was examined. In this procedure the aqueous sample is distilled in the presence of a mixture of methanol and aqueous sulfuric acid. The methanol-acrylonitrile azeotrope, boiling at 61.4 °C, distils first from this mixture and thus the acrylonitrile is recovered in the initial distillate. 

The azeotropic-distillation procedure was tested by using a synthetic solution of acrylonitrile in water that had been shown by direct polarographic analysis to contain 0.75 ppm of acrylonitrile. A measured volume (500 ml) of this solution, i.e., 0.375 mg of acrylonitrile, together with 5 ml of concentrated sulfuric acid, 25 ml of methanol and 0.1 g of 2,4-dinitrophenyl-hydrazine (to destroy carbonyl compounds) 

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