VG (Vegetable Glycerin) The Base makes up 80-90% of e-juice and is composed of 100% VG or a mix with PG. Common ratios are 100% VG, 50/50 PG/VG, and 80/20 PG/VG. It is widely used in all types of food and personal care products like toothpaste. http://en.wikipedia.org/wiki/Glycerol
PG (Propylene glycol) Commonly mixed with VG as the base for e-juice. This is a solvent that’s used in all sorts of things. Along with being a solvent, its mainly known for its use in fog machines. A higher PG mix e-juice will produce thicker clouds of vapor. However PG can dry out your throat and even cause mild allergic reactions in some users. If you have any issues with PG, just use a 100% VG e-juice like those from Virgin Vapor http://en.wikipedia.org/wiki/Propylene_glycol
Flavor 10%-20%. All the e-juice I’ve seen uses Food grade flavorings originally intended for baking or candy making. Here is an excerpt from the LorAnn website: “All of our materials are food grade (where applicable) and adhere to standards set down in the USP, NF or FCC (U.S.Pharmacopoeia, National Formulary, and Food Chemical Codex).”
Nicotine 0%-2.4% depending on strength. Any large supplier of e-juice is using pharmaceutical grade pure nicotine.
Distilled water is sometimes used to dilute if needed.