The ethyl-hexadecyl members of a homologous series of 2,4-dichlorobenzyl alkyl ethers were prepared using the Williamson Ether Synthesis and purified by chromatographic methods. Temperature programmed gas chromatographic retention indices were calculated for a range of chromatographic conditions of column stationary phases, temperature programme rates, and starting temperatures for wall-coated open tubular columns. The n-alkanes were used as retention index standards. The DCBE retention indices were used to calibrate a gas chromatographic identification system for organochlorine pesticides and polychlorinated biphenyls and their utility was demonstrated in the identification and measurement of organochlorine residues in a series of fish oils from North Atlantic catches.