The analytical process was optimized for the determination of individual PCBs in a commercial mixture, Delor 104, and in soil samples contaminated by PCBs. The optimal analytical conditions for the GC-MS system with a DB-5 capillary column involved a temperature program evaluated in terms of information content I(S) and information flow I(S)/t and an identification procedure based on the correlation analysis of the measured and published relative retention r 1 2 data.