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: hiPS - CMs were seeded onto MEA and FPD was measured for 2min every 10min for 30min after drug exposure for the vehicle and each drug concentration .
### Output Text:
hiPS - CMs were seeded onto MEA and FPD was measured for 2min every 10min for 30min after drug exposure for the vehicle and each drug concentration . 