Potential for exaggeration of PCB contents of packaged fish by phthalates from the wrapping material or solvents

A convenient method for recovering PCBs from lipids is to digest the matrix in concentrated H2SO4 and recover the unaffected PCBs into hexane for determination by gas chromatography with electron capture detection. In a recent fish analysis case the peaks for these PCBs were accompanied by a large component identified as di-(2-ethylhexyl) phthalate, shown to have migrated into Fsh lipid from a heavy plastic wrap, and only partly destroyed by the H2SO4. The di-n-butyl and di-(2-ethylhexyl) phthalates bracket the major Aroclor peak region of chromatograms on a methyl silicone GC column and possibly a di-n-hexyl phthalate ester would very likely be superimposed directly on the PCBs. In the course of this work it was found that commercially available hexanes of presumed high quality contained the same di-(2-ethylhexyl) phthalate plasticizer in proportions high enough to be of concern in such analyses.