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: RESULTS : The incidence and severity of visible muscle fasciculation was significantly less with increasing the amount of precurarizing dose of rocuronium ( P < 0 . 001 ) .
### Output Text:
RESULTS : The incidence and severity of visible muscle fasciculation was significantly less with increasing the amount of precurarizing dose of <span class="chemical">rocuronium</span> ( P < 0 . 001 ) . 