Laboratory grade products are made for scientific research only. They are not meant to be consumed - as seen on the warning by laboratory suppliers. In addition, the purchase of these products, especially nicotine, requires a license. The reason behind are concerns of contamination. Products are made in the same area and purified on the same machines as other potentially toxic chemicals. In fact, manufacturer has warned not to eat, drink or smoke when using this product.
Pasted below are some warnings on the use of laboratory nicotine by a leading laboratory chemical manufacturer
For research purpose only.
Keep container tightly closed in a cool place
Keep in a cool well-ventilated place away from ... (incompatible materials to be indicated by manufacturer)
Keep only in the original container in a cool well-ventilated place away from ... (incompatible materials to be indicated by manufacturer)
When using, do not eat, drink or smoke
Avoid contact with skin and eyes
After contact with skin, take off immediately all contaminated clothing and wash immediately with plenty of.... (to be specified by the manufacturer)
Do not empty into drains, dispose of this material and its container to hazardous or special waste-collection point
Wear suitable protective clothing, gloves and eye/face protection
Given the tight regulation in the US (as I have been told), the origin of the nicotine may not even be laboratory grade.