16922
When azide ion forms contact ion pairs with cations in dimethylsulfoxide ( DMSO ) , free azide ion and contact ion pairs are spectrally well distinguished in FTIR spectra .
 Chemical: azide; Chemical: dimethylsulfoxide; Chemical: DMSO; Chemical: azide
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: azide, dimethylsulfoxide, DMSO, azide 
Answer:
 Chemical: azide; Chemical: dimethylsulfoxide; Chemical: DMSO; Chemical: azide