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 , only secretory granules showed the positive reaction products for prolactin 6 h after bromocriptine treatment of the adenoma cells .
### Output Text:
However , only secretory granules showed the positive reaction products for prolactin 6 h after <span class="chemical">bromocriptine</span> treatment of the adenoma cells . 