Chlorpyrifos Reference Standards
HPC supplies chlorpyrifos (CAS 2921-88-2) as neat material and solvent solutions, plus D10-chlorpyrifos for isotope-dilution methods. EU and US regulatory positions differ and are stated separately below.
Product | Catalog No./ CAS No. | Quantity | Price | |
|---|---|---|---|---|
ISO 17034 Certified Reference Material Chlorpyrifos solution |  | 673526 | 1X5ML | Please log in. |
ISO 17034 Reference Material |  | 673986 | 1X250MG | Please log in. |
ISO 17034 Certified Reference Material Chlorpyrifos solution |  | 674487 | 1X10ML | Please log in. |
ISO 17034 Certified Reference Material Chlorpyrifos solution |  | 675397 | 1X5ML | Please log in. |
ISO 17034 Certified Reference Material |  | 687727 | 1X100MG | Please log in. |
 | 676734 | 1X20MG | Please log in. | |
ISO 17034 Certified Reference Material D10-Chlorpyrifos solution |  | 676738 | 1X1ML | Please log in. |
ISO 17034 Certified Reference Material D10-Chlorpyrifos solution |  | 678119 | 1X5ML | Please log in. |
Identity and analytical relevance
Chlorpyrifos is an organophosphate insecticide. It is also called chlorpyrifos-ethyl in some regulatory and technical documents and must not be confused with chlorpyrifos-methyl.
- CAS Registry Number: 2921-88-2
- Molecular formula: C9H11Cl3NO3PS
- Molecular weight: 350.6 g/mol
European Union status and health basis
The European Commission did not renew the EU approval of chlorpyrifos on 10 January 2020. Member States were required to withdraw authorisations for plant-protection products containing the active substance. The Commission records that the decision followed human-health concerns identified by EFSA and Member-State experts, particularly possible genotoxicity and developmental neurotoxicity. EFSA concluded that safe exposure levels could not be determined from the available data and that the EU human-health approval criteria were not met.
The Commission subsequently lowered EU food and feed MRLs to the lowest levels measurable by analytical laboratories, with the lower values applying from around October 2020. The exact legal value remains commodity-specific and must be taken from the current EU pesticides database or consolidated legislation.
United States status
The US position is different. According to the EPA update dated 6 January 2026, the 2021 rule revoking all chlorpyrifos tolerances was vacated by a federal court and the tolerances are currently in effect. EPA expects further rulemaking that would revoke tolerances for all but 11 crop uses, subject to additional restrictions. Existing product cancellations and label restrictions remain relevant. This US status does not alter the EU non-renewal.
Available HPC reference materials
The current range includes neat chlorpyrifos, 10.0 and 100 µg/mL solutions in acetonitrile, a 100 µg/mL solution in ethyl acetate, and D10-chlorpyrifos as neat material or 100 µg/mL solutions in acetone or acetonitrile. Use the item-specific certificate to confirm concentration, uncertainty, solvent and storage conditions.
Primary sources and review status
- PubChem: chlorpyrifos identity and molecular data
- European Commission: chlorpyrifos non-renewal, health basis and MRL action
- US EPA: current chlorpyrifos food-use and tolerance update
Regulatory information reviewed on 16 July 2026. Confirm the current rule for the relevant commodity, use, product label and jurisdiction before applying it.