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 treatment with CBZ had no apparent adverse effect on folate concentrations in the rat , and , indeed , the folate concentration increased in liver after 6 weeks of treatment and in plasma at 8 weeks of treatment .
### Output Text:
This treatment with <span class="chemical">CBZ</span> had no apparent adverse effect on <span class="chemical">folate</span> concentrations in the rat , and , indeed , the <span class="chemical">folate</span> concentration increased in liver after 6 weeks of treatment and in plasma at 8 weeks of treatment . 