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: We conclude that 125 mg i . v . MP should be given routinely before and after TDI of iron dextran .
### Output Text:
We conclude that 125 mg i . v . <span class="chemical">MP</span> should be given routinely before and after TDI of <span class="chemical">iron dextran</span> . 