19770
Four constituents were isolated from heat - processed G . pentaphyllum using resin HP - 20 , silica gel and reversed ODS column chromatography .
 Chemical: silica gel
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: silica gel