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: Patients were randomized to receive 0 . 02 , 0 . 03 , 0 . 04 , 0 . 05 and 0 . 06 mg / kg rocuronium as a precurarizing dose .
### Output Text:
Patients were randomized to receive 0 . 02 , 0 . 03 , 0 . 04 , 0 . 05 and 0 . 06 mg / kg <span class="chemical">rocuronium</span> as a precurarizing dose . 