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: Postoperatively , she was given a patient - controlled analgesia device delivering boluses of diamorphine 0 . 5 mg and droperidol 0 . 025 mg .
### Output Text:
Postoperatively , she was given a patient - controlled analgesia device delivering boluses of <span class="chemical">diamorphine</span> 0 . 5 mg and <span class="chemical">droperidol</span> 0 . 025 mg . 