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: Explicit episodic memory for sensory - discriminative components of capsaicin - induced pain : immediate and delayed ratings .
### Output Text:
Explicit episodic memory for sensory - discriminative components of <span class="chemical">capsaicin</span> - induced pain : immediate and delayed ratings . 