Dioxin-like PCBs Contamination Analysis

Dioxin-like PCBs are a group of PCBs congeners that show "dioxin-like" toxicity including non-ortho and mono-ortho PCBs. They are also known as persistent environmental pollutants (POP). The toxicity of the PCBs is determined by the chlorination pattern. These dioxin-like PCBs have only one or no chlorine atom at the ortho-position.

Figure 1. Chemical structure of dioxin-like PCBs and related food products

Dioxin-like PCBs widely exist in the environment and are unwanted byproducts. A number of industrial processes such as the burning process of wood, fuels and coal can produce dioxin-like PCBs. Dioxin-like PCBs are very persistent and not easy to break down in the environment. The reduction on the dioxin-like PCBs emission is required by the regulatory agencies.

Dioxin-like PCBs with high levels have been reported to be associated with fish products due to the bioaccumulation in the food chain from the dioxin-like PCBs sediments in the environment. Foods can be contaminated by dioxin-like PCBs from the environment. They are highly soluble in fat resulting in potential high levels in fatty foods. There are a number of studies on the increased levels of dioxin-like PCBs in many food products and they have risen the recognition of the relevance for the exposure of the general public to these dioxin-like PCBs.

Dioxin-like PCBs have toxicity on the immune and reproductive system of human beings. They have negative impact on the development of central nervous system and the growth of organisms. They are also harmful to the thyroid hormones. Short-term exposure to dioxin-like PCBs with high levels may cause damage to skin. Dioxin-like PCBs have been proved to have carcinogenicity in several animal studies.

The World Health Organization (WHO) specified the maximum levels for the sum of dioxin-like PCBs in a variety types of foods. The contamination limits were set as 1.5 pg/g for vegetable oils and fats, 3.0 pg/g for mixed animal fats, 6.0 pg/g for eggs and dairy products, and 8.0 pg/g for fish and fishery products. Low levels of dioxin-like PCBs have to be detected in the food products.

The procedure for the analysis of dioxin-like PCBs in foods includes sample preparation and extraction, clean-ups, and detection/quantification. We control sample preparation factors and have extensive steps for sample clean-up step. We have expertise in the sample preparation of a variety types of food matrices. The sample preparation has significant effect on the accuracy of the level measured in the food samples.

WHO has listed 12 coplanar PCBs congeners that have dioxin-like toxicity and molecular structure. The analysis of dioxin-like PCBs is similar as the testing of dioxin and PCBs. We offer accurate and validated analytical methods that have been widely applied in the determination of dioxin-like PCBs in food samples to meet customers' needs.

Gas chromatographs coupled with mass spectrometer (GC-MS)

GC-MS is used in the EPA method, and more often used for the quantification of planar PCB congeners.

We also maintain high quality assurance for the analysis. The recovery of internal standard, the use of blanks and spikes is monitored for each batch of analysis.