" Diethylthiophosphate is the most frequent metabolite of organophosphorus (OP) found in urine Organophosphorus compounds are widely used as pesticides because of easy degradation in the environment. Acute OP intoxication results from blockage of the decomposition of synaptic acetylcholine because the pesticide covalently binds to chlolinesterase Chronic exposure to POs has neurological sequelae as well and data suggests that OP exposure alters sperm chromatin condensation."

From T3DB  webpage.....

Okay, So I am not a chemist, so take this for what it is worth.  However, when it says "...most frequent metabolite..."   what I think it is saying is that Deithylthiophosphate is a compound that is produced when another product - in this case, an organophosphate compound - is broken down..... in other words, metabolized.  So, if you are looking on a label for the name "diethylthiophosphate", you won't find it.

Start taking a look at organophospate insecticides - Lorsban will be the most common example. Malathion is also an organophosphate insecticide. These products may likely produce Diethylthiophosphate.  Again, I am not chemist, but that would be a good place to look.

Find a list of organophosphate insecticides, and see which ones you have used.  Wiki has this list. 

edit: I did not know what Hel-Fire is.   So, I found it.  It is an "aminated phosphoric acid and carboxylic acid".  Based on that, I would ask questions about what it develops when it breaks down.  I don't know if an "aminated Phosphoric acid" would break down similar to an organophate insecticide.  But I would ask questions.  I good place to start might be with a an entomologist or chemist as your land-grant university.

That is my thought.