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: METHODS : We investigated the effect of varying the intraperitoneal infusion rates of bupropion HCl 120 mg / kg , a known convulsive dose 50 ( CD50 ) , on the incidence and severity of bupropion - induced convulsions in the Swiss albino mice .
### Output Text:
METHODS : We investigated the effect of varying the intraperitoneal infusion rates of <span class="chemical">bupropion HCl</span> 120 mg / kg , a known convulsive dose 50 ( CD50 ) , on the incidence and severity of <span class="chemical">bupropion</span> - induced convulsions in the Swiss albino mice . 