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: However , the oral dose of d , l - sotalol was significantly lower in patients with torsades de pointes ( 200 + / - 46 vs . 328 + / - 53 mg / day ; p = 0 . 0017 ) .
### Output Text:
However , the oral dose of <span class="chemical">d , l - sotalol</span> was significantly lower in patients with torsades de pointes ( 200 + / - 46 vs . 328 + / - 53 mg / day ; p = 0 . 0017 ) . 