Polarography acrylonitrile

Applications As the basic process of electron transfer at an electrode is a fundamental electrochemical principle, polarography can widely be applied. Polarography can be used to determine electroreductible substances such as monomers, organic peroxides, accelerators and antioxidants in solvent extracts of polymers. Residual amounts of monomers remain in manufactured batches of (co)polymers. For food-packaging applications, it is necessary to ensure that the content of such monomers is below regulated level. Polarography has been used for a variety of monomers (styrene, a-methylstyrene, acrylic acid, acrylamide, acrylonitrile, methylmethacrylate) in... 

Styrene, acrylonitrile Styrene-acrylonitrile Solution in DMF, polarography [502,506-508]... 

Methacrylonitrile can also be determined if acrylonitrile is absent. Both styrene and acrylonitrile can also be determined in acrylonitrile-butadiene-styrene terpolymers, using the same procedure. Tetrabutylammonium iodide (0.1 M TBAI) in aqueous dimethylformamide (DMF) was used as the base electrolyte and polarography was carried out using a differential cathode ray polarograph. 

For dilute solutions, both gas chromatography (66) and polarography (67) are rapid, sensitive, and precise. Small amounts of acrylonitrile can be separated from other components by azeotropic distillation with alcohols, followed hy polaro-graphic (67,68) or chromatographic (69,70) analysis. 

Styrene-acrylonitrile copolymers Aqueous, alcoholic, oily Acrylonitrile monomer Polarography [87, 88]... 

Methods have been described for determining styrene and acrylonitrile (dimethyl formamide extraction-polarography) and styrene, acrylonitrile and butadiene monomers (solution in dimethyl formamide-gas clnomatography). Acrylonitrile has been determined by polarography and by gas chromatography of a dimethyl formamide solution. The polarographic method also determines methacrylonitrile. Styrene monomer has been determined by a polarographic method. ... 

METHOD 55 - DETERMINATION OF STYRENE AND ACRYLONITRILE MONOMERS IN STYRENE - ACRYLONITRILE COPOLYMERS. CATHODE-RAY POLAROGRAPHY ... 

W = weight in g. of original styrene - acrylonitrile copolymer sample made up to 50 cm in base electrolyte solution (5 cm portion used for polarography)... 

Determination of styrene and acrylonitrile monomers in styrene-acrylonitrile copolymers. Cathode-ray polarography... 

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 methanol azeotropic-distillation procedure was also applied to a synthetic solution of acrylonitrile in 6% hydrochloric acid extractant. Polarographic analysis of the methanol-acrylonitrile azeotrope was not possible, however, owing to the presence of an appreciable amount of free acid originating from the hydrochloric acid extractant, in the distillates, which interfered in the polarography of acrylonitrile. In a further experiment, a 6% hydrochloric acid solution of 47.3 ppm of acrylonitrile was neutralised by the addition of a small excess of solid calcium oxide. Methanol and sulfuric acid were added and the azeotropic distillation continued as before. It can be seen from Table 11.1 (sample B) that under these conditions more than 90% of the added amount of acrylonitrile was recovered in the first 8 ml of methanol distillate. A preliminary neutralisation with lime was incorporated, therefore, into the procedure for determining acrylonitrile in 6% hydrochloric acid extraction liquids. This procedure should also be applicable to the determination of acrylonitrile in the 3% aqueous acetic acid extractant recommended by the Food and Drug Administration (FDA) [3]. 

Procedures, based on these principles, involving extraction with water and azeotropic distillation with methanol before polarography should also be applicable to the -heptane extractant recommended by the FDA [3] and also might be useful for the determination of acrylonitrile in the FDA vegetable oil extractants, provided that these can be successfully extracted with water. Trials have not been made on these particular extractants. 

---