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 : All dosage groups consisted of three women , except those with 100 microg ( n = 6 ) and 200 microg ( n = 18 ) .
### Output Text:
RESULTS : All dosage groups consisted of three women , except those with 100 microg ( n = 6 ) and 200 microg ( n = 18 ) . 