16720
On the basis of the intensities of the spectral changes and inhibition of P450 2A13 , we classified the 68 chemicals into eight groups based on the order of affinities for these chemicals and inhibition of P450 2A13 .
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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