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: This result was not due to altered disposition of either APAP or acetylated metabolites in plasma or renal cortical and hepatic tissue .
### Output Text:
This result was not due to altered disposition of either <span class="chemical">APAP</span> or acetylated metabolites in plasma or renal cortical and hepatic tissue . 