The base is actually 50/50, which accounts for the difference we got in grams. According to Google the great, you got an accurate reading for PG specific gravity, but VG is denser at about 1.26 g/ml. That makes 50/50 roughly 1.15 g/ml (unless you want to be really accurate and factor in the density of the nicotine), so 2 ml * 1.15 g/ml = 2.3 g.