19499
Here we use a classic deuterium exchange reaction to replace the C2 - H hydrogen atom of the His imidazole ring with deuterium , leading to a unique aromatic C2 - D stretching vibration whose frequency is sensitive to environmental changes across the entire imidazole ring .
 Chemical: deuterium; Chemical: C2 - H; Chemical: hydrogen; Chemical: His; Chemical: imidazole; Chemical: deuterium; Chemical: C2 - D; Chemical: imidazole
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: deuterium, C2 - H, hydrogen, His, imidazole, deuterium, C2 - D, imidazole 
Answer:
 Chemical: deuterium; Chemical: C2 - H; Chemical: hydrogen; Chemical: His; Chemical: imidazole; Chemical: deuterium; Chemical: C2 - D; Chemical: imidazole