Thanks for the link Stephen. This is a link to the full paper and some quotes:
The sensory attribute most associated with nicotine is described within the company as 'impact' . It may be described by consumers as
throat catch, throat hit, throat grip, etc. Our definition of impact is : the sudden sharp but short-lived sensation (typically less than one second in duration) which is noticed immediately the smoke makes contact with the back of the throat . A physiological explanation of the impact sensation is that nicotine causes smooth muscle to contract . The contraction is proportional to the dose of nicotine applied to it. In fact, the relationship between the applied dose and the magnitude of the contraction is logarithmic, but for all practical purposes, the more nicotine the stronger the contraction and hence the impact sensation.
http://www.health.gov.bc.ca/guildford/pdf/bat/122/00012275.pdf
That definition suggests that zero nicotine eliquid cannot produce a throat hit.
