IMPA (Isopropyl Methylphosphonic Acid)
Definition
The primary hydrolysis product of sarin (GB). Detected in urine of sarin-exposed individuals and in environmental matrices by GC-MS and LC-MS/MS. The primary biomarker for sarin exposure in the OPCW verification analytical framework; detectable in urine for up to 72 hours post-exposure by standard methods.
- Degradation path
- Primary hydrolysis product formed when sarin breaks down through the isopropoxy-phosphorus bond.
- Detection window
- Detectable in urine for up to 72 hours post-exposure using standard analytical methods.
- OPCW status
- Schedule 1 OPCW verification analyte, designated for sarin exposure confirmation in international chemical weapons investigations.
Common questions
What is IMPA and why do forensic labs test for it?+
IMPA is isopropyl methylphosphonic acid, the main breakdown product of sarin (a nerve agent) in the human body and environment. Forensic labs use it as a biomarker to confirm sarin exposure. When sarin breaks down through hydrolysis, it creates IMPA, making it a reliable indicator that someone or something was exposed to sarin.
How long can IMPA be detected after sarin exposure?+
IMPA can be detected in urine for up to 72 hours after sarin exposure using standard detection methods. It remains in environmental samples as well, making it useful for investigating contaminated sites.
What techniques do labs use to detect IMPA?+
Forensic labs typically use LC-MS/MS (liquid chromatography paired with tandem mass spectrometry) and GC-MS (gas chromatography paired with mass spectrometry) to detect IMPA in urine samples and soil extracts. These are precision analytical methods recognized by the Organization for the Prohibition of Chemical Weapons (OPCW) for chemical weapons verification.
Related terms
- OPCW Designated Laboratory
- A laboratory authorised by the Organisation for the Prohibition of Chemical Weapons to conduct official CWC verification analysis. Must pass biennial proficiency...
- 31P NMR
- Phosphorus-31 nuclear magnetic resonance spectroscopy, used to confirm the presence of phosphorus-containing OP nerve agents and their degradation products. Diagnostic: chemical shift...
- Acetylcholinesterase (AChE) Inhibition
- The primary mechanism of toxicity for all organophosphate nerve agents, including sarin, VX, and Novichok compounds. The agent phosphorylates the serine residue...
- AChE (Acetylcholinesterase)
- The enzyme that terminates cholinergic nerve impulses by hydrolysing acetylcholine. Irreversibly phosphorylated at Ser203 by OP nerve agents, causing accumulation of acetylcholine...
- Alpha Spectrometry
- An analytical technique for measuring the energy spectrum of alpha particles emitted by radionuclides. Used in the Litvinenko investigation to detect and...
- Chemical Weapons Convention (CWC)
- The international treaty prohibiting the development, production, stockpiling, and use of chemical weapons, in force since 1997 with 193 states parties. Implemented...
- DRDE Gwalior
- The Defence Research and Development Establishment in Gwalior, Madhya Pradesh, India. The primary national laboratory for chemical agent detection, characterisation, and protective...
- Novichok
- A class of organophosphate nerve agents developed under the Soviet Union's Foliant programme, structurally distinct from G-series (sarin, tabun, soman) and V-series...
- Novichok (A-Series)
- A class of Soviet-era phosphoramidate nerve agents (A-230, A-232, A-234) from the Foliant programme. Reported to be 5-10x more toxic than VX....
- Nuclear Forensics
- The analysis of nuclear or other radioactive material and related evidence to determine the material's origin, history, and intended use. Uses isotope-ratio...
- OCAD (OPCW Central Analytical Database)
- The OPCW's reference library of confirmed GC-MS and NMR spectra for all scheduled chemicals and their degradation products, used by Designated Laboratories...
- Polonium-210 (Po-210)
- An alpha-emitting radionuclide (half-life 138.4 days) produced by neutron bombardment of bismuth-209. Used as the weapon in the Litvinenko murder. Detectable at...
Explained in these topics
- Chemical Warfare Agents and the OPCW Designated Laboratory NetworkThe primary environmental and urinary degradation product of sarin, formed by hydrolysis of the isopropoxy-phosphorus bond. A Schedule 1 OPCW verification anal...
- CWA, Dirty Bomb and RDD Investigative ReadinessThe primary hydrolysis product of sarin (GB). Detected in urine of sarin-exposed individuals and in environmental matrices by GC-MS and LC-MS/MS. The primary b...