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 the double blind study with haloperidol , both substances were found to be highly effective in the treatment of psychotic syndromes belonging predominantly to the schizophrenia group .
### Output Text:
In the double blind study with <span class="chemical">haloperidol</span> , both substances were found to be highly effective in the treatment of psychotic syndromes belonging predominantly to the schizophrenia group . 