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: Drug - induced immune hemolytic anemia was suspected because of positive direct antiglobulin test , negative eluate , and microspherocytes on smear pre - and post - transfusion .
### Output Text:
Drug - induced immune hemolytic anemia was suspected because of positive direct antiglobulin test , negative eluate , and microspherocytes on smear pre - and post - transfusion . 