7489
The exogenous and exogenous estrogens were analyzed by gas chromatography combustion isotope ratio mass spectrometry ( GC - C - IRMS ) to determine the ( 13 ) C / ( 12 ) C ratio ( delta ( 13 ) C /1000 ) .
 Chemical: estrogens; Chemical: ( 13 ) C; Chemical: ( 12 ) C; Chemical: ( 13 ) C
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: estrogens; Chemical: ( 13 ) C; Chemical: ( 12 ) C; Chemical: ( 13 ) C