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: Noradrenergic involvement in catalepsy induced by delta 9 - tetrahydrocannabinol .
### Output Text:
Noradrenergic involvement in catalepsy induced by <span class="chemical">delta 9 - tetrahydrocannabinol</span> . 