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: In a randomized , double - blind trial , 90 women were allocated to receive one of three treatments prior to induction of anaesthesia with propofol .
### Output Text:
In a randomized , double - blind trial , 90 women were allocated to receive one of three treatments prior to induction of anaesthesia with <span class="chemical">propofol</span> . 