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: RESULTS : Of 60 epileptic women with periconceptional folic acid ( 0 . 8 mg ) - containing multivitamin supplementation , no one developed epilepsy - related side effects during the periconception period .
### Output Text:
RESULTS : Of 60 epileptic women with periconceptional <span class="chemical">folic acid</span> ( 0 . 8 mg ) - containing multivitamin supplementation , no one developed epilepsy - related side effects during the periconception period . 