气相色谱-质谱法测定塑料制品中多环芳烃

GC-MS Determination of Polycyclic Aromatic Hydrocarbons in Plastics

将正己烷-二氯甲烷（2＋1）混合溶剂加入于塑料样品中，在水浴中于室温下超声萃取30min，所得溶液在控温30℃的水浴中用旋转蒸发浓缩至2mL，并将此溶液通过硅胶柱净化分离。先用正己烷淋洗硅胶柱以洗去非极性的正构烷烃，然后以正己烷-二氯甲烷（3＋2）混合溶剂淋洗，所得洗脱液先经旋转蒸发浓缩至2mL，再用氮气吹拂浓缩至恰为1．0mL，此溶液供气相色瞥质谱分析之用，对相应的分析条件也作了详述。由于采用了先旋转蒸发后氮气吹拂的浓缩方法，不仅使蒸发时间缩短，而且减少了低沸点多环芳烃（PAH）的挥发损失。按所提出的方法测定了塑料中16种PAH，方法的检出限（3S／N）小于0．01mg·kg^-1。选用一种含PAH甚少的塑料样品作为基体，加入3个浓度水平含16种PAH的混合标准溶液按方法操作进行回收试验，测得回收率在87．2％～100．2%之间，测定值的相对标准偏差（n=7）在1．3％～5．8％之间。

Polycyclic aromatic hydrocarbons （PAH） were extracted ultrasonically from plastic samples with a mixed solvent of n-hexane and dichloromethan （2＋1） in a water bath at room temperature for 30 min. The extract was concentrated to 2 mL by evaporation in water bath at 30 ℃ and purified by passing through silica gel column. After removing the non-polar n-alkanes by rinsing with n-hexane, PAH on the column were eluted with n-hexane and diehloromethane （3＋2） mixture, and the etuate collected was concentrated to 2 mL by evaporation and to 1 mL further by mild nitrogen blowing. The solution obtained was used in GC-MS analysis for the 16 PAH. The use of rotary evaporation and nitrogen blowing in succession, not only hasten the concentration of the eluate but also lessen the volatilizing loss of those low boiling PAH. Detection limits （3S/N） of the method found was less than 0. 01 mg · kg^-1 , for all the 16 PAH. Recovery was tested by addition of mixed standard solution of the 16 PAH at 3 concentration levels to a substantial plastics sample, values of recovery obtained were in the range of 87. 2%- 100. 2% , with values of RSDts （n=7） in the range of 1.3%-5.8%.