提出了顶空气相色谱法快速测定食品包装用丙烯腈-苯乙烯共聚物和橡胶改性树脂及成型品中1,3-丁二烯、丙烯腈、苯乙烯、甲苯和乙苯5种残留单体和溶剂的分析方法。取粒状或碎片状样品1 g置于顶空瓶中,然后加入3 mL DMF并密封。按规定的程序将溶液引入仪器进行分析。采用DB-WAX毛细管色谱柱,在50 ℃~180 ℃范围内按程序升温进行分离,测定时用FID检测。方法的测定下限(10S/N)为0.036~3.8 mg·kg-1。用标准加入法测得回收率在90.8%~98.0%,测定值的相对标准偏差(n=6)均小于3%。应用此方法分析了丙烯腈-苯乙烯(AS)及1,3-丁二烯-丙烯腈-苯乙烯(ABS)塑料样品各4个,结果显示:样品中除了含有国标规定限量的丙烯腈残留单体外,还含有大量的苯乙烯单体,及一定含量的乙苯和甲苯,存在一定的食品安全隐患。

Head-space-GC was applied to the determination of 5 residual monomers and solvents, i.e., 1,3-butadiene, acrylonitrile, styrene, toluene and ethylbenzene, in styrene-acrylonitrile copolymers and rubber modified resins, as well as in their products used as food packaging materials. The sample (1.00 g in form of granules or slices) was treated in a sealed 20 mL head-space bottle with 3 mL of DMF, and the solution was introduced into the instrument and analyzed as the prescribed conditions, DB-WAX capillary column was used for separation under programmed temperature elevation from 50 ℃ to 180 ℃, and FID was used for determination. Lower limits of determination (10S/N) of the method were found in the range of 0.036-3.8 mg·kg-1 for the 5 compounds. Values of recovery found by standard addition were ranged from 90.8% to 98.0% with RSD′s (n=6) less than 3%. Four samples each of the AS and ABS plastics were analyzed by the proposed method, as shown by the experimental results, besides limited amounts of acrylonitrile, definite amounts of toluene and ethylbenzene as well as relatively high contents of styrene were also found, which were hiddeen dangers against food safety.