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: The aim of this study is to investigate the effects of propofol in intralipid or medialipid emulsions on bupivacaine - induced cardiotoxicity .
### Output Text:
The aim of this study is to investigate the effects of <span class="chemical">propofol</span> in intralipid or medialipid emulsions on <span class="chemical">bupivacaine</span> - induced cardiotoxicity . 