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: Despite adequate oral dosage of DPH ( 5 mg / kg / daily ) the plasma level was very low ( 2 . 8 microgramg / ml ) .
### Output Text:
Despite adequate oral dosage of <span class="chemical">DPH</span> ( 5 mg / kg / daily ) the plasma level was very low ( 2 . 8 microgramg / ml ) . 