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: In conclusion , glutamate and capsaicin yield reproducible hyperalgesic and allodynic responses , and the present model is well suited for basic research , as well as for assessing the modulation of central phenomena .
### Output Text:
In conclusion , <span class="chemical">glutamate</span> and <span class="chemical">capsaicin</span> yield reproducible hyperalgesic and allodynic responses , and the present model is well suited for basic research , as well as for assessing the modulation of central phenomena . 