Naphtha is a mixture of different hydrocarbons. In my experience, every company has several different formulations, VM&P being the most prefered. The formulas in my area often contain hexane, a nasty neurotoxin, so I don't use it. In addition to doing an evaporation test to see if your brand leaves behind any residue, I recommend checking the label to see if contains hexane. If it does, consider your options, or look into what you can do to minimize exposure through vapor and skin contact.
Heptane is safer to use, but ime, evaporates quite quickly, even in a sealed glass container in the freezer. Nexians often recommend its use for recrystalizations.
