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: Those of myalgia tend to decrease according to increasing the amount of precurarizing dose of rocuronium , but there was no significance ( P = 0 . 072 ) .
### Output Text:
Those of myalgia tend to decrease according to increasing the amount of precurarizing dose of <span class="chemical">rocuronium</span> , but there was no significance ( P = 0 . 072 ) . 