Sunday, August 11, 2013

JFK Scare: Analytical Chemistry at the Airport

Please see below for updates as I receive further information...

As reported by multiple news outlets (CNN, Daily Mail, The Atlantic), a 'suspicious package' leaked an unknown substance* onto two customs inspectors at JFK International Airport Sunday afternoon. When the workers fell ill, the FBI quarantined two facilities - one customs, one mail sorting - and tested the material.

Initial assays indicated potential organophosphate chemical weapons. Later tests, however, confirmed that the substance was actually phosphoric acid, leaking from a faulty cosmetics package. The two inspectors, after receiving on-scene treatment, declined further medical attention.

A few points about this story (emphasis mine):
  • Most news agencies reported hesitantly, but not the Daily Mail, which declared: "The package from China tentatively tested positive for VX nerve gas, which can be used as a weapon of mass destruction..." (They even included a strangely-rotated space-filling model of VX in the article!)
I'd be quite interested to know how the FBI field tests for organophosphate nerve agents (Sorry, Daily Mail, but VX, due to its high boiling point and viscosity, is actually not a gas but a thick liquid much like phosphoric acid). I'm aware of certain colorimetric pesticide test strips, and certainly blood chemistry assays for exposed individuals would tell the tale.

But could phosphoric acid give a false positive here? Its chemical properties aren't overall very similar to nerve agent. Unlike VX, phosphoric acid has acidic protons, rendering a much different reactivity and solubility profile. VX soaks deep into skin due to its carbon appendages - hence, organophosphate - which wouldn't really occur with the acid. Perhaps JFK sent a sample out for 31P NMR? This analytical technique would show a resonance close to that of VX, which might incite a high-threat response. Perhaps an LC-MS might also ring warning bells: both compounds should show a fragment around 94 m/z.
  • The Atlantic cheerfully summarized: "It turns out what made the two men sick was actually organophosphate, an ingredient in soda pop."
If I ever find organophosphate in my Coke can, I'm suing. That is, if I survive the encounter...

Organophosphates, to which VX, sarin, soman, and several potent insecticides belong, have alkylated (carbon-functionalized) bonds on their oxygen atoms. Once ingested or absorbed, they tend to interfere with acetylcholinesterase, an enzyme involved in neural signaling. The reporter perhaps meant to say "phosphorus compound" or even "acid," but unfortunately chose the wrong word.

One more thing: I completely understand the highly cautious nature of the law enforcement response. Organophosphates can sicken or kill at remarkably low doses, thus their unfortunate appeal as terror weapons. If any of my readers have experience with airport chemical detection, please write in to set me straight on your detection methods of choice.

Update, 8/12/13 - Changed "parent peak" to "fragment"

*Update 2, 8/12/13 - Chemjobber points out, via Twitter, that the NY Post reported ordinary nail polish remover (usually acetone, or ethyl acetate / iPA) as the culprit. Now I'm even more confused as to how this triggered a nerve agent analytical read!

Update 3, 8/12/13 - Commenters on Reddit and JLC (thanks!) remark that airports have at their disposal DART-based benchtop MS, or perhaps Barringer IONTRAP ion mobility spectrometers. Another commenter suggests M8-M9 detection paper. Vibrational spectroscopy (Raman, IR, etc) has been bandied about as well.

6 comments:

  1. If any of these potential compounds had been properly packaged and marked the inspectors would have had a much easier time confirming what the material was. The various crime show dramas aside, the rapid identification of a completely unknown chemical substance is tricky at best.

    ReplyDelete
    Replies
    1. A terrorist would never properly package and mislabel a chemical agent?

      Delete
  2. It wouldn't surprise me if initial on-site testing was done with a device something along the lines of M9 tape. It's used for detection of various chemical weapons in combat situations, and is widely used by the military. It's quite prone to false positives and overly broad classification though. For instance, some insecticides (DEET among them, I believe) can test as VX (I think they call it "VX Type" in the documentation).

    It's been a while since I worked with it so I can't recall the nitty gritty, and Google isn't as helpful as I had expected, but it might explain the head scratcher of a false positive.

    ReplyDelete
    Replies
    1. I'd be curious to know how M9 tape works as well. The only nerve agent detection reagents I know of work by undergoing phosphorylation with the nerve agent followed by an intramolecular elimination to give colored/fluorescent products. You could maybe get false positives with acid chlorides, but I wouldn't want to breath those in either.

      Delete
  3. CoulombicExplosionAugust 12, 2013 11:02 AM

    I'm not sure if JFK has this instrumentation or not, but my understanding is that it is becoming increasingly common.

    http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=626268&url

    Identification is done via drift-time (analogous to retention-time on LCs or GCs)matching against a library. Good for initial screening, but definitely susceptible to false positives.

    ReplyDelete
  4. Ion mobility spectroscopy (as mentioned above) is the technique of choice (at UK airports at least).

    It stands to reason that a flavour of vibrational spectroscopy may have been used, the equipment is very small these days and there is precedence for a database to spit out VX as a "close match" to orthophosphate's, obviously a skilled vibrational spectroscopist would notice the lack of NH and CN bonding modes, not sure that law enforcement officers are Raman interpretation trained though . .

    http://rta.biz/images/customer-files/ApplSpec-2005-VX.pdf

    ReplyDelete