There is an effective maximum density for freebase nicotine(most common, and lowest density type of vape juice), but there is a separate type called nicotine sa

There is an effective maximum density for freebase nicotine(most common, and lowest density type of vape juice), but there is a separate type called nicotine salts that are vastly more concentrated, in the ~50-60 mg/mL range. Nicotine salts are widely used in Juuls and other products like the Suorin Air.