Procept® - Eichrom

PCDD/F compound containing a specific number and pattern of chlorine substituents) based on the ability
of the congener to bind to the AhR, elicit AhR-mediated biochemical and toxic responses and be
persistent and accumulate in the food chain. These seventeen PCDD/F congeners have been assigned
toxicity equivalent factors (TEFs) relative to the most toxic congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin.
In standard gas chromatography mass spectrometry (GC-MS) determinations, toxicity equivalent
quotients (TEQ) of PCDD/F containing samples are determined by taking the sum of the concentrations
of each PCDD/F congener multiplied by its TEF.
The PROCEPT ® assay utilizes the affinity of the aryl hydrocarbon receptor for PCDD/F
compounds, forming complexes composed of PCDD/F, the AhR, an aryl hydrocarbon nuclear translocator
protein (ARNT) and a specific DNA response element (DRE). This complex is then bound to a plastic strip
coated with a polyclonal antibody specific for the c-terminus of the ARNT. Excess AhR, ARNT and DNA
are washed away and the amount of DNA is amplified and measured using real-time polymerase chain
reaction (PCR). The output of the PCR instrument is threshold cycle (Ct). The Ct is the number of PCR
temperature cycles at which the measured fluorescence for a given sample/standard exceeds a threshold
value. By comparing the Ct of an unknown sample to the Ct values of a standard curve generated from 5-
7 concentrations of 2,3,7,8-TCDD, the TEQ of the sample can be determined.
The degree of interaction of individual PCDD/F congeners with the AhR is proportional to the TEF
established by the WHO, therefore, the amount of DNA measured by the PCR is proportional to the
PCDD/F TEQ of the sample. However, the PROCEPT ® assay does not provide information on the
amount of each individual PCDD/F congener.
Several other classes of aryl hydrocarbon compounds also interact with the AhR, including
polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and brominated and mixed
brominated/chlorinated dibenzo-p-dioxins and furans. Therefore, in order to measure PCDD/Fs using the
AhR-PCR assay, a sample preparation method capable of separating PCDD/Fs from other AhR active
compounds is necessary. A complete list of cross-reactivity values and appropriate sample preparation
methods can be found in literature available at www.eichrom.com/dioxin/products.
D. Intended Use
The Procept Rapid Dioxin Assay is an Aryl-hydrocarbon (AhR) based polymerase chain reaction (PCR)
assay for the measurement of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in prepared
sample extracts. Samples should be prepared for measurement by the Procept Assay using an approved
method for isolating PCDD/F from the sample matrix (see methods available from Eichrom Technologies
LLC at www.eichrom.com/dioxin/products). Consult the notes listed below in this package insert and
literature available at the Eichrom Technologies website for limitations of this method.
Note: The Procept Rapid Dioxin Assay measures total PCDD/F response which correlates with the TEQ
of the sample. The Procept Assay will not provide information on the concentration of individual PCDD/F
congeners present in the sample.
Note: The AhR used in this method binds to PCDD/F and similar molecules based on structure, not mass.
Therefore, 13 Carbon- or other stable isotope labeled standards are detected to the same degree as native
compounds. These labeled standards cannot be used as internal standards with this method.
Note: The Procept Rapid Dioxin Assay is designed for screening of samples according to their TEQ by
responding to PCDD/F congeners in proportion to their concentration and TEF value. However, the
response factors for individual PCDD/F congeners on the AhR-PCR assay are not identical to the TEF
values assigned by the world health organization (WHO). Therefore, variation in the accuracy among
samples may occur solely because of variability in congener composition. Quantitative interpretation of
the data may be possible in certain situations. However, confirmation of positive identification of PCDD/F
contamination and a portion of negative samples by GC-MS is strongly recommended.
E. Instructions for Use of Kit
1. Sample Extraction and Purification
www.eichrom.com 11/5/07 page 2 of 7