Do you have any proof of that assertion?
EDIT: I just called Wizard Labs and this appears to be true. At least with them. They said there are 0 sources presently of U.S. made nicotine
juice. They get theirs from several countries, one of which is China. However, they do test all the liquids they obtain in-house before using or sending it anywhere.
RTS does get their nicotine from a local North Carolina source and another in Pennsylvania. Wizard Labs for the most part gets theirs from China and India. I saw a report elsewhere on ECF that documented where the overwhelming vast majority of nic in the US is originally sourced from China.
I currently have nic concentrates in my freezer from this E-Liq site shipped from the US, also from their parent company shipped directly from China, from RTS, and 3 varieties from Wizard Labs (standard, Ultra, & ICE). I have tested all of them via titration and the % advertised was accurate on all. I diluted each of them down to a 50/50 (pg/vg) 36mg solution and vaped them without flavor in a side by side taste test to see if I liked any particular one above the other. Quite frankly there wasnt a lot of difference between any of them. The Ultra and the ICE from Wizard Labs had less of the peppery notes, I personally like the peppery thing, but that is just a personal preference. None of the solutions tasted bad or "off", and any difference was slight, I would be hard pressed to select a significant winner.
To me it all then boiled down to my confidence in the handling practices of the lab doing the packaging. I am HIGHLY confident in Wizard Labs, very confident of RTS, fairly confident of the US based E-liq site, and cautious of the Chinese shipped product. This is based on reputation, my own personal titration tests, and tasting.
All of that being said, if "I" were to place an order today, with Wizard Labs current prices there is no advantage in buying from the Chinese based discounter. I would buy from Wizard Labs as their reputation is beyond reproach and they also throw in a freebie sample of something on every shipment. However, if US based E-Liqs price were significantly lower, I would not hesitate to buy from them either. RTS is currently more expensive than either of the other two but there is nothing wrong with their product, they also had nic when many others were out of stock.
EDIT: For what its worth, playing into that whole "confidence factor" thing for me, is that Wizard Labs was head and shoulders above ANYBODY else I have dealt with when it came to bottling, labeling, packing for shipment, etc. Everything about the transaction was truly Laboratory grade.