21708
Preconcentration procedure under the optimum conditions was applied to water , vegetable and fruit samples to determine Pb , Cd and Ni in trace levels .
 Chemical: Pb; Chemical: Cd; 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: Cd; Chemical: Ni