40 CFR § 766.27 - Congeners and LOQs for which quantitation is required.

---
identifier: "/us/cfr/t40/s766.27"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 766.27 - Congeners and LOQs for which quantitation is required."
title_number: 40
title_name: "Protection of Environment"
section_number: "766.27"
section_name: "Congeners and LOQs for which quantitation is required."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "R"
subchapter_name: "TOXIC SUBSTANCES CONTROL ACT"
part_number: "766"
part_name: "DIBENZO-PARA-DIOXINS/DIBENZOFURANS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "15 U.S.C. 2603 and 2607."
regulatory_source: "52 FR 21437, June 5, 1987, unless otherwise noted."
cfr_part: "766"
---


# 766.27 Congeners and LOQs for which quantitation is required.

Quantitation at the target LOQ shown for each of the following HDDs/HDFs which may be present in the chemical substances is required for the chemical substances listed under § 766.25. Analysis must take place for either chlorinated or brominated dibenzodioxins or dibenzofurans, whichever is predominantly expected to occur in the chemical substance to be tested. Only chlorinated and brominated congeners need be quantified; for chemical substances containing predominantly chlorine atoms, only congeners totally chlorinated at the numbered positions need be quantified; for chemical substances containing predominantly bromine atoms, only congeners totally brominated at the numbered positions need be quantified.

| Chlorinated dioxins | Brominated dioxins | LOQ |
| --- | --- | --- |
| 2,3,7,8-TCDD | 2,3,7,8-TBDD | 0.1 ppb. |
| 1,2,3,7,8-PeCDD | 1,2,3,7,8-PeBDD | 0.5 ppb. |
| 1,2,3,4,7.8-HxCDD | 1,2,3,4,7,8-HxBDD | 2.5 ppb. |
| 1,2,3,6,7,8-HxCDD | 1,2,3,6,7,8-HxBDD | 2.5 ppb. |
| 1,2,3,7,8,9-HxCDD | 1,2,3,7,8,9-HxBDD | 2.5 ppb. |
| 1,2,3,4,6,7,8-HpCDD | 1,2,3,4,6,7,8-HpBDD | 100 ppb. |
| 2,3,7,8-TCDF | 2,3,7,8-TBDF | 1 ppb. |
| 1,2,3,7,8-PeCDF | 1,2,3,7,8-PeBDF | 5 ppb. |
| 2,3,4,7,8-PeCDF | 2,3,4,7,8-PeBDF | 5 ppb. |
| 1,2,3,4,7,8-HxCDF | 1,2,3,4,7,8-HxBDF | 25 ppb. |
| 1,2,3,6,7,8-HxCDF | 1,2,3,6,7,8-HxBDF | 25 ppb. |
| 1,2,3,7,8,9-HxCDF | 1,2,3,7,8,9-HxBDF | 25 ppb. |
| 2,3,4,6,7,8-HxCDF | 2,3,4,6,7,8-HxBDF | 25 ppb. |
| 1,2,3,4,6,7,8-HpCDF | 1,2,3,4,6,7,8-HpBDF | 1 ppm. |
| 1,2,3,4,7,8,9-HpCDF | 1,2,3,4,7,8,9-HpBDF | 1 ppm. |