Any strong acid would do.
Sulphuric is recommended only because it's readily available.
Are there any convenient sources of sulfuric acid that are available possibly locally without having to source it through a chemical supply house?
Is muriatic acid a possible substitute?
I should have RTFM, muriatic acid IS hydrochloric acid. Ooops.
Sodium Bisulfate, when dissolved in water becomes a complex of sulfuric acid and sodium sulfate. I use it successfully in my bleach. I find it easier to handle, measure, clean up, etc.
You can find some at a pool supply store. It is sometimes sold as "pH down".
Thanks for the heads up. Not that I have anything to hide from the DEA but I find that filling out that form and subjecting myself to their scrutiny would not be worth it in the least for 100ml of sulfuric acid.
You can buy sulfuric acid at an auto supply shop. They keep it behind the counter. It is used to top off lead-acid batteries. Just figure out the concentration and dilute down.
BTW, I wouldn't concern yourself with the DEA form. Do you know how many people fill those out every day? You are a grain of salt in the ocean.