This is right. C's N has been tested in the past various times by members on the Exit forum by Energy Control in Spain.
energycontrol-international.org
If you buy 25 grams of N from C, the purity (the concentration of pentobarbital in the N) will be in the 60-67% range.
The rest is filler.
This can of course always be subject to change, that's why it's recommended to always test N powder.
Years ago there was another seller from China named Johnson in the PPH.
He begin with selling 25 grams of N with a purity level of 75% pentobarbital but then he started cutting it up and finally ended up selling 25 grams of N with a purity level of only 20% pentobarbital. He was kicked out of the PPH for scamming.
It's the one clear advantage Liquid N has over powder.
Since you're buying a brand made in a medical factory, you know exactly what you're getting if the bottle is sealed and has never been opened.