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: METHODS : Patients that received Botox injections for spasmodic dysphonia between January 2000 and October 2009 were evaluated .
### Output Text:
METHODS : Patients that received <span class="chemical">Botox</span> injections for spasmodic dysphonia between January 2000 and October 2009 were evaluated . 