CLEANUP BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF POLYCHLORODIBENZO-P-DIOXINS AND POLYCHLORODIBENZOFURANS ON A PYRENYLETHYLSILICA GEL COLUMN

A clean-up step prior to the determination of polychlorodibenzo-p-diox ins (PCDDs) and polychlorodibenzofurans (PCDFs) based on normal-phase HPLC on a 2-(1-pyrenyl)ethyldimethyl silylated silica column is presen ted. With hexane as mobile phase, polychlorobiphenyls (including highl y chlorinated non-ortho isomers) and organochlorine pesticides are elu ted in the first fraction. The total fraction of PCDDs and PCDFs can b e eluted by backflushing. By application of a gradient, all congeners are eluted within 75 min. The retention order of the PCDDs and PCDFs i s predominantly governed by the degree of chlorination, but the substi tution pattern also has a strong influence. Subfractions of the PCDD/P CDF fraction can be taken. The fraction containing 2,3,7,8-tetrachloro dibenzo-p-dioxin was isolated. The three tetrachlorodibenzo-p-dioxin i somers of this fraction were baseline separated on a non-polar capilla ry GC column.