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: Assessment of a new non - invasive index of cardiac performance for detection of dobutamine - induced myocardial ischemia .
### Output Text:
Assessment of a new non - invasive index of cardiac performance for detection of <span class="chemical">dobutamine</span> - induced myocardial ischemia . 