I don't know what nicotine river uses either (I think some of the processes are proprietary) but they do state they don't use benzoic acid, if that's a concern. You might be able to email them for more information (if you explain your situation they may be more helpful). I do not find nic river's nic salts to be irritating to my lungs, and I was in pretty darn rough shape when I got here. I used them for LACK of throat hit, as my entire respiratory system was just shot and my throat hurt all the time. I'd probably be okay with freebase by now, and I will be finding that out at some point in the future (just opened a liter of nic river nicsalts, but when it's done, I will try mixing with freebase I got down the line (as it is cheaper).
There is a process to convert freebase nic yourself using citric or malic acid, and the process doesn't sound crazy complicated, if you want to "know for sure" what is in your nic salts. If I don't like freebase, I'll probably convert them to salt, myself.
Also, yes, if your lungs are sensitive to vape right now, you can get plenty of nic absorption without inhaling, probably the best way to do maximize absorption without a full inhale would be in through the mouth, out through the nose. Our sinus cavities are enormous and a great way to absorb nic. I did FULL nasal vaping (inhale by sticking the drip tip up my nose, and then exhale through my nose, after some oral surgeries where I did NOT want to apply suction OR nicotine.)
I was shocked at how little nic I needed for some pretty good absorption. I used far less eliquid during that time (full disclosure, I was also passed out during that time from pain a lot, I don't use opiates) however, even with that, well, I got a lot of absorption from a small amount of eliquid.
I didn't continue vaping that way, it's not super enjoyable but I do enjoy exhaling vapor through my nose, and I use my sinus cavities because they are a great mechanism for absorption.
If your lungs are irritated you might try that style of vaping for a bit and slowly work you way into a full inhale, if that's your desire and etc. I'd had pneumonia for 18 months straight pretty much, as I quit smoking, and inhaling was a bit rough for a while, although it's perfectly fine now. Also, depending on your style of vape you could try a more restricted vape with les vapor production, that may help also.
Best of luck,
Anna
