I have always been annoyed at the idea that how diluted the solution is determines how long it lasts. The net amount that a person is exposed to should determine the effects.
If I'm exposed to 1 gram of 1% pheromone, that's 10mg of pheromone in my system. If I'm exposed to 1mg of 100% pheromone, that's 1mg of pheromone in my system. An undiluted spray has a better likelihood of delivering more pheromone given the same delivery, but the delivery system in the show was not very controlled. Getting sprayed straight in the face with a diluted solution should have greater effect than being doused with a 100% solution from several hundred feet up, where it has time to mix with all that air and have some of it blow away.
I don't think that a higher exposure to the point of becoming permanent would cause actual genetic changes, which would then be passed on to the next generation. I imagine that it would cause a permanent change to the brain chemistry such that the victim would never recover from the effects. The implication in the episode seemed to be that the greater the percentage of solution, the longer the effects would last. Realistically, though, I would think that the effects wouldn't last very much longer but rather would be more potent. Think about when you take one tablet of tylenol, and it lasts for 6 hours or so, but if you're in lots of pain, you take two tablets, which give you more pain relief but still only last about 6 hours.
Actually the amount of the medicine in said tablet (ex. 100 mg vs 200 vs. 400 etc.) determines both strength and duration, and my theory is that the pheromone works in a similar fashion (in that sense).
I guess what I'm trying to say (and probably failing) is that 1% might be the closest she gets to an "optimal" dosage while 2% given of the same dosage would last longer in the system, because there would be more of the effective ingredient in the system.
I thought I might post this up here as it kind of explains what I'm trying to say:
Formula for calculating dosage
