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: Acetaminophen ( up to 150 micrograms / mL ) did not retard the incorporation of radioactive adenosine into ATP in slices of rat cerebral cortex .
### Output Text:
<span class="chemical">Acetaminophen</span> ( up to 150 micrograms / mL ) did not retard the incorporation of radioactive <span class="chemical">adenosine</span> into <span class="chemical">ATP</span> in slices of rat cerebral cortex . 