GC-MS Determination of Polycyclic Aromatic Hydrocarbons in Plastics

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 dichloromethane (3+2) mixture,and the eluate 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 RSD′s (n=7) in the range of 1.3%-5.8%.