What is Jet-A made of?
Sadly, that information's pretty much impossible to give a general answer for, as it changes from batch to batch:


Refineries blend crude "to taste" as well as pricetag, so to speak, and the crude blend used as the refinery feedstock may change from batch to batch.
Process conditions in catalytic crackers and reformers can change depending on the point in the batch you're at, the incoming feedstock, and even the history of prior batches (say the last thing that ran through the cat cracker degraded the catalyst slightly...)
Jet fuels as-delivered may be a blend of multiple refinery batches and even the output of multiple refiners
Pipeline batching can also lead to subtle changes in fuel composition as it is transported -- pipeline operators try to "cut off" as much of the transmix as they can, but 100% isn't easy without wasting tons of fuel as transmix.  (Some pipeline operators will stick a "dumb pig" between high spec products, such as jet fuel, and their neighbors in the pipeline, but this is by no means universal.)


That said, you can make some determinations based off of a representative SDS for Jet-A, courtesy of ConocoPhillips:


The fuel consists of medium-weight hydrocarbons, from C9 to C16
The only specified aromatic component is napthalene, with a maximum concentration of 3%
No additives (anti-static, FSII, anti-oxidation, biocidal) are specified -- these are generally variable from batch-to-batch, depending on the specific purchaser (a large airport might get to spec these directly with the refiner, while the small GA 'dromes are at the mercy of whoever pulls up in the fuel truck)