Chemical Analysis

If this is your first time here, I recommend starting from the conclusion page.

In this post I will examine evidence relating to the chemicals used in the attack.

Of course, the most important evidence is the UN reportwhich reported finding sarin in the Zamalka area and in blood samples. The report further provides more detailed results from two labs, but did not provide any analysis. So let's try and analyze it ourselves.

Stabilizers

Sarin manufactured for military use requires storage for extended periods and therefore contains chemical stabilizers. Alternatively it can be kept as two precursors (binary form), that are mixed when the projectile is in-flight. For this to work the projectile needs to have a barrier that is removed or broken at deployment, and then spin to mix the materials. Since the sarin UMLACA was determined to be a converted White Phosphorus weapon, and does not seem to be spin-stabilized, it is very unlikely to support this process.

Therefore, lack of stabilizers should indicate the sarin did not come from military storage and was prepared shortly before the attack. There seem to be three types of sarin stabilizers: dibutylchloramine, tributylamine and diisopropylcarbodiimide. None of them appear in the UN Report (Appendix 7). Furthermore, all chemicals listed are linkable to sarin by-products, sarin degradation products or traces of explosives (see more below).

In a comment, Gleb Bazov referred me to this report, showing Iraq had a process of mixing binary weapons manually before launch, thus avoiding the use of stabilizers. However, this seems like a non-standard and risky process, which could be attributed to Iraq's low quality nerve agent program. 

Sarin by-Products

Finding Sarin by-Products in samples is an indication of low-quality production. Sarin is produced through several stages, and each step requires matching exact quantities of the reacting chemicals. If this is not done professionally, remains of earlier steps will react with later stage chemicals, and produce undesired impurities in the final product, which will reduce its efficiency and shelf-life. Advance chemical weapons programs, such as Syria is believed to have, should produce sarin with very low levels of impurities.

A careful reading of the Appendix brings up an interesting find. While Lab 1 has a column marked “Degradation Products and by-Products”, Lab 2 reports “Degradation Products” alone (Degradation products are chemicals created from the exposure of sarin to the environment). Both labs then have a column for “Other interesting chemicals”. Interestingly, Lab 1 has nothing listed under “Other”, while Lab 2 has a long list of chemicals there. So since these chemicals are not listed as sarin degradation products, they may be the sarin by-products we're looking for.

To verify this claim, let’s examine some of these chemicals:

1. Ethyl isopropyl methylphosphonate
2. Isopropyl methyl methylphosphonate
3. Isopropyl propyl methylphosphonate
4. Diisopropyl dimethylpyrophosphonate (Update: this is more likely a degradation product)
5. Dimethyl methylphosphonate

The other chemicals seem to be traces of explosives (specifically, RDX and TNT). See here a more detailed discussion of the many findings of Hexamine. See here a discussion of Hexafluorophosphate.

To try and make sense of these without getting too technical, let’s examine a very simplified sarin production process:

1. Take Phosphorus
2. Add Methyl groups (and Oxygen)
3. Add Chlorine
4. Replace the Chlorine with Fluoride
5. Add Isopropyl Alcohol (aka Isopropanol)

Our final product has Phosphorus, Methyl, Fluoride and Isopropyl.

So since all our chemicals contain a methyl group (or ethyl - see below), isopropyl and phosphorous compounds, it seems that these are all remains of step 2 that didn’t react at steps 3 and 4, and instead reacted at step 5.

And just to make the evidence more compelling, Item 5 (Dimethyl methyl phosphonate) is actually the exact result of one of the steps in the production of sarin (i.e. it survived all later interactions).

Update

DDTea has provided a detailed professional analysis in the comments below (Thank you again!). His main findings:

1. Sarin was indeed impure.
2. The finding of an ethyl group in by-product 1 (Ethyl isopropyl methylphosphonate) indicates the isopropanol used in the last stage of production was "technical grade" (i.e. the cheapest).
3. The last stage of production was done on site, thus avoiding stabilizers.

Eyewitness Reports

Another good indication for the sarin's production process are reports about odors at the site of the attack. When produced professionally, sarin is odorless (and colorless). Odors would therefore indicate impurities.

Zamalka victims provided numerous eyewitness reports, and they were near unanimous in their descriptions of weird odors. Examples:

1. "vinegar and rotten eggs"
2. "cooking gas"
3. "overpowering smell"
4. "insecticide"
5. "unpleasant smell", "yellowish color"
6. "the smell was quite strong that I could not recognize it at all. It was a little bit like the smell of burning"
7. "rotten smell"
8. "a smell of gas-like odor, or sulfur, but you do not feel the smell too much"
9. "a strong sulfur-like smell, and a foggy white color"
10. “strange smell”

Comparing this to the Halabja military chemical attack in 1988, which involved mustard gas (brown-yellow color, garlic smell), sarin (odorless), tabun (fruit smell) and VX (odorless), shows a much more "correct" depiction of odors:

1. "sweet apples"
2. "It was just like the smell of garlic."
3. yellowish smoke smelling of "bad garlic" or "rotten apples"
4. “pleasant smell in the air; smell of sweet apples, orange, and garlic”
5. "We thought it was home gas, like garlic and gas from the kitchen"
6. "it was like apples but also other kinds of fruit."
7. "aroma that reminded me of apples"
8. "It was similar to rotting garbage, but then it changed to a sweet smell similar to that of apples. Then I smelled something that was like eggs."
9. "smelled like sweet apples"

The difference is even more interesting when considering that Iraq's nerve agents were later found to have high level of impurities.

In the Tokyo Sarin Attack, which used very low quality sarin, eyewitnesses reported either not noticing a smell or "odors like burning rubber or mustard".

Update: Further analysis found stronger evidence of low-budget production.

Conclusion: The sarin used in Zamalka was produced in an immature process, which is inconsistent with the Syrian regime's chemical program.

Did I miss anything? Please share your evidence and analysis and help me improve my conclusions. 


Appendix - Sarin Process

For those who like to get technical, here's an example of a full sarin production process. Click on each step's product for more details (from Wikipedia):

1. White Phosphorus + Chlorine = Phosphorus Trichloride
2. Phosphorus Trichloride + Methanol = Trimethyl Phosphite
3. Trimethyl Phosphite + Halo-Methane = Dimethyl Methylphosphonate
4. Dimethyl Methylphosphonate + Thionyl Chloride = Methylphosphonic Dichloride
5. Methylphosphonic Dichloride + Potassium Fluoride or Hydrogen Fluoride or Sodium Fluoride = Methylphosphonyl Difluoride
6. Methylphosphonyl Difluoride + Isopropanol / Isopropyl alcohol (+ Isopropylamine to neutralize Hydrogen Fluoride)  = sarin

Item 3 was the one found by the UN on site.