Comparison of immunoaffinity column recovery patterns of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans on columns generated with different monoclonal antibody clones and polyclonal antibodies

Evaluation of immunoaffinity columns (IACs) for dioxin serum sample clean-up requires a determination of the recovery of various dioxin congeners. We compared the IAC performance of different monoclonal and polyclonal anti-dioxin antibodies, measuring the recovery of congeners of polychlorinated dibenzo-p-dioxins (PCDDs). In addition, we measured the recovery of congeners of the structurally related polychlorinated dibenzofurans (PCDFs). The polyclonal antibody based IACs evaluated had lower recovery for highly chlorinated dioxin congeners, but were more specific toward 2,3,7,8-TCDD. The resemblance of the hapten to 2,3,7,8-TCDD appeared to play a clear role, but chlorines in the 2-, 3- and 7-positions of the hapten were essential. Recovery of 2,3,7,8-TCDD from the IAC showed some relation to the affinity for the antibody measured by either the K_a from accelerator mass spectrometry (AMS) or with 50% inhibition of color activity (IC₅₀) determined from an ELISA analysis. The IACs prepared from four monoclonal antibodies (Mabs) derived from a common hapten showed differences in their retention patterns of PCDDs/PCDFs. Comparison of IC₅₀ from ELISA with recovery from the IACs indicated that a minimum IC₅₀ of 100ppb was required for satisfactory recovery from the IAC, but the correlation was poor, indicating other factors were involved. Mab DD3 showed the broadest spectrum of the Mabs and showed satisfactory recoveries of all of the dioxin congeners, except OCDD. In addition, DD3 showed good recovery toward 2,3,4,8-TCDF, 2,3,4,7,8-PeCDF and 2,3,4,6,7,8-HxCDF but has poor recovery when PCDFs have a chlorine substitution in the 1-position.