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: CONCLUSIONS : The epileptic pregnant patient ' s autoimmune disease ( probably drug - induced lupus ) could damage the blood - brain barrier , therefore the therapeutic dose ( > or = 1 mg ) of folic acid triggered a cluster of seizures .
### Output Text:
CONCLUSIONS : The epileptic pregnant patient ' s autoimmune disease ( probably drug - induced lupus ) could damage the blood - brain barrier , therefore the therapeutic dose ( > or = 1 mg ) of <span class="chemical">folic acid</span> triggered a cluster of seizures . 