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: One female patient with stable cardiac disease had recurrent torsades de pointes after 2 years of successful treatment with d , l - sotalol .
### Output Text:
One female patient with stable cardiac disease had recurrent torsades de pointes after 2 years of successful treatment with <span class="chemical">d , l - sotalol</span> . 