23543
Nicotine brain levels were 30 and 14 ng / g at 1 and 2 h after treatment .
 Chemical: Nicotine
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Nicotine 
Answer:
 Chemical: Nicotine