14311
This tailor - made optical sensor permits ultra - fast ( <= 60 s ) , specific , pH - dependent visualization and removal of Cu ( 2 + ) , Cd ( 2 + ) , and Hg ( 2 + ) at sub - picomolar concentrations ( ~ 10 ( - 11 ) mol dm ( - 3 ) ) from aqueous media , including drinking water and a suspension of red blood cells .
 Cu ( 2 + ), Cd ( 2 + ), Hg ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Cu ( 2 + ), Cd ( 2 + ), Hg ( 2 + )