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: Maximal platelet aggregation induced by 6 microM of adenosine diphosphate decreased after administration of ketoprofen .
### Output Text:
Maximal platelet aggregation induced by 6 microM of <span class="chemical">adenosine diphosphate</span> decreased after administration of <span class="chemical">ketoprofen</span> . 