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: The prompt discontinuation of D - penicillamine and vigorous treatment measures could allow for a good prognosis as in this case .
### Output Text:
The prompt discontinuation of <span class="chemical">D - penicillamine</span> and vigorous treatment measures could allow for a good prognosis as in this case . 