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: The 0 . 25 per cent CHP cream was closest to AgSD in pain tolerance ; however , none of the treatments differed statistically from AgSD or from each other .
### Output Text:
The 0 . 25 per cent <span class="chemical">CHP</span> cream was closest to <span class="chemical">AgSD</span> in pain tolerance ; however , none of the treatments differed statistically from <span class="chemical">AgSD</span> or from each other . 