17844
Structure elucidations were mainly achieved by spectroscopic methods ( 1H - NMR , 2D - NMR , MS ) and by comparison with authentic references .
 Chemical: 1H
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 1H