Complex matrices may occur in product process waste streams that can interfere with gas Chromatographic analysis of priority pollutants. Most interferences can be eliminated by simple column clean‐up procedures, pH change, direct aqueous analysis, or the use of selective detectors. Other interferences may require clean—up by molecular weight distribution, separation by capillary columns, or the use of pre‐columns and back‐flushing techniques. This paper suggests logical steps to follow when encountering these interferences.