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: Liver and plasma TBARs were not increased until 14 days ( 2 - fold vs . control , p < 0 . 05 ) .
### Output Text:
Liver and plasma <span class="chemical">TBARs</span> were not increased until 14 days ( 2 - fold vs . control , p < 0 . 05 ) . 