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: However , this response was correlated with an elevated number of striatal [ 3H ] spiperone binding sites , whereas the number of striatal L - [ 3H ] nicotine binding sites and the striatal DA level were normal .
### Output Text:
However , this response was correlated with an elevated number of striatal [ 3H ] <span class="chemical">spiperone</span> binding sites , whereas the number of striatal L - [ 3H ] <span class="chemical">nicotine</span> binding sites and the striatal <span class="chemical">DA</span> level were normal . 