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: Phenylpropanolamine ( PPA ) is a sympathetic amine used in over - the - counter cold remedies and weight - control preparations worldwide .
### Output Text:
<span class="chemical">Phenylpropanolamine</span> ( <span class="chemical">PPA</span> ) is a sympathetic <span class="chemical">amine</span> used in over - the - counter cold remedies and weight - control preparations worldwide . 