6384
The optimum parameters for Pb and Ni were found to be 3 . 5 , 30 min and 2 . 5 mL for pH , contact time , eluate volume , respectively .
 Chemical: Pb; Chemical: Ni
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: Pb; Chemical: Ni