In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : Prilocaine may be preferable to lidocaine for short surgical procedures because it has a similar duration of action but a lower incidence of TNSs .
### Output Text:
CONCLUSIONS : <span class="chemical">Prilocaine</span> may be preferable to <span class="chemical">lidocaine</span> for short surgical procedures because it has a similar duration of action but a lower incidence of TNSs . 