2464
In practice , for two similar suspensions , half - life decreases from 4 . 1 +/- 1 . 10h to 2 . 5 +/- 0 . 77h before and after purification .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None