Nicotine mixed with PG/VG in the U.S. is different from nicotine
extracted from the
tobacco in the U.S.
Companies that say their nicotine base/liquid is made in the U.S. are referring to mixing the full-strength nicotine into the base liquid (PG/VG) or are just mixing in flavors to a nicotine base liquid in the U.S. But the nicotine itself currently comes from other countries.
As far as we are aware, Wizard Labs and other companies that sell nicotine base mix the full-strength nicotine with PG/VG here in the U.S., but uses nicotine extracted and imported from other countries. That in no way means that there is anything wrong with the nicotine. Third-party testing is done to rate purity and 99.2% pure nicotine from China is just as pure as 99.2% nicotine from Ireland or from the U.S. - once they start extracting it here again. Nicotine base (already mixed with PG/VG) from other countries, on the other hand, may not meet those same standards.
At least, that is what my research on the subject has found.