Editing Sarin (section)

==Degradation and shelf life==
[[File:Sarin test rabbit.jpg|thumb|upright|Rabbit used to check for leaks at former sarin production plant ([[Rocky Mountain Arsenal]]), 1970]]

The most important chemical reactions of phosphoryl halides is the hydrolysis of the bond between phosphorus and the fluorine atom. This P-F bond is easily broken by nucleophilic agents, such as water and [[hydroxide]]. At high [[pH]], sarin decomposes rapidly to nontoxic [[phosphonic acid]] derivatives.<ref>{{cite web |title=Nerve agents |publisher=OPCW |url=http://www.opcw.org/about-chemical-weapons/types-of-chemical-agent/nerve-agents/}}</ref><ref>{{Housecroft1st|page=317}}</ref> The initial breakdown of sarin is into isopropyl methylphosphonic acid (IMPA), a chemical that is not commonly found in nature except as a breakdown product of sarin (this is useful for detecting the recent deployment of sarin as a weapon). IMPA then degrades into [[methylphosphonic acid]] (MPA), which can also be produced by other organophosphates.<ref>Ian Sample, ''[[The Guardian]]'', September 17, 2013, [https://www.theguardian.com/world/2013/sep/17/sarin-deadly-history-nerve-agent-syria-un Sarin: the deadly history of the nerve agent used in Syria]</ref>

Sarin with residual acid degrades after a period of several weeks to several months. The shelf life can be shortened by impurities in [[precursor (chemistry)|precursor materials]]. According to the [[CIA]], some [[Iraqi chemical weapons program|Iraqi sarin]] had a shelf life of only a few weeks, owing mostly to impure precursors.<ref>{{cite web |publisher=United States Central Intelligence Agency |date=July 15, 1996 |title=Stability of Iraq's Chemical Weapon Stockpile |url=https://fas.org/irp/gulf/cia/960715/72569.htm |access-date=August 3, 2007}}</ref>

Along with nerve agents such as [[Tabun (nerve agent)|tabun]] and [[VX (nerve agent)|VX]], sarin can have a short shelf life. Therefore, it is usually stored as two separate precursors that produce sarin when combined.<ref>{{cite news |title=Key Points on Sarin: The 'Most Volatile' of Nerve Agents |author=Russell Goldmanpril |date=April 6, 2017 |newspaper=New York Times |url=https://www.nytimes.com/2017/04/06/world/middleeast/sarin-nerve-agent.html}}</ref> Sarin's shelf life can be extended by increasing the purity of the precursor and intermediates and incorporating [[stabilizer (chemistry)|stabilizers]] such as [[tributylamine]]. In some formulations, tributylamine is replaced by [[diisopropylcarbodiimide]] (DIC), allowing sarin to be stored in [[aluminium]] casings. In [[binary chemical weapon]]s, the two precursors are stored separately in the same [[shell (projectile)|shell]] and mixed to form the agent immediately before or when the shell is in flight. This approach has the dual benefit of solving the stability issue and increasing the safety of sarin munitions.