23627
Serum and cerebrospinal fluid concentrations of K203 were determined using ion - pair reversedphase chromatography on octadecyl silica column .
 Chemical: octadecyl silica
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: octadecyl silica 
Answer:
 Chemical: octadecyl silica