500mg/ml is a pretty high concentration man so just be ready for it to potentially crash if you don't get the ph just right. i usually use 0.9% benzyl alcohol as a preservative and it works fine. definitely use distilled water or sterile water for injection if you can get it.

bulksupplements is alright for some things but for injectable stuff you gotta be really careful about the purity since it’s technically "food grade." i’ve heard some guys say it works fine but i always worry about heavy metals or weird fillers when i'm pinning it IM.

honestly 500mg/ml is gonna bite lol. the higher the concentration the more it tends to sting after the injection. i personally prefer 250 or 300mg/ml because i can actually walk the next day without my leg feeling like i got kicked by a horse.

make sure you use a 0.22um syringe filter or youll end up with an abscess for sure. even if the raws look clean there could be tiny particles in there you cant see. for the recipe i just do carnitine, bac water, and a tiny bit of ba. super simple.

i've used bulksupps for my oral carnitine for years but i’d be a bit sketched out about brewing it for pins. maybe try to find a more "reputable" raw source if you can- check the boards for guys who specifically sell raws for brewing. it's worth the extra few bucks for peace of mind.

good luck with the brew man! just a tip- keep the heat low when your dissolving it. if you cook it too hot it might turn a weird yellow color and smell funky. once it's clear and filtered your good to go.