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: This case represents an example of " idiosyncratic " drug - induced liver damage in which the primary target of injury is the bile duct .
### Output Text:
This case represents an example of " idiosyncratic " drug - induced liver damage in which the primary target of injury is the bile duct . 