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: Cromakalim was approximately 8 - to 9 . 5 - fold more potent than pinacidil in increasing CxAD .
### Output Text:
<span class="chemical">Cromakalim</span> was approximately 8 - to 9 . 5 - fold more potent than <span class="chemical">pinacidil</span> in increasing CxAD . 