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: However , identification of a short - acting local anesthetic to substitute for lidocaine for brief surgical procedures remains an important goal .
### Output Text:
However , identification of a short - acting local anesthetic to substitute for <span class="chemical">lidocaine</span> for brief surgical procedures remains an important goal . 