The Isomer Distribution and Congener Profile of Polychlorinated Dibenzo-P-Dioxins (PCDDs) in Ball Clay from the Mississippi Embayment (Sledge, Mississippi)
Several recent studies have found elevated levels of polychlorinated dibenzo-p-dioxins (PCDDs) in chickens and farm raised catfish grown in the United States resulting from the use of contaminated animal feed. The dioxins were discovered to have originated from the ball clay used as an anti-caking agent in the soybean meal component of the feed. This ball clay was mined from an area geologically referred to as the Mississippi Embayment. However, the source and/or origin of the dioxins in this ball clay have yet to be discovered.
A useful method to help identify the source of an unknown chemical mixture like polychlorinated dibenzo-p-dioxins/-furans is to determine the distribution of the various congeners within a particular homolog group and to develop a profile of all the 2,3,7,8-chlorine substituted congeners. They can then be compared to the profiles and distributions of the PCDDs/PCDFs of known sources. Quite often the isomer distribution and congener profile is very characteristic of a particular source and is often referred to as a "chemical fingerprint". This information can be used as a means to help identify the origin of the material.
The congener profile and isomer distribution of PCDDs/PCDFs in the Mississippi ball clay has been established on a DB-5 analytical column and the chromatograms of the various congeners displayed using DB-5MS column.