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: On the Positive and Negative Syndrome Scale positive subscale , all treatments were superior to placebo with LOCF and MMRM ; asenapine at 5 mg BID was superior to placebo on the negative subscale with MMRM and on the general psychopathology subscale with LOCF and MMRM .
### Output Text:
On the Positive and Negative Syndrome Scale positive subscale , all treatments were superior to placebo with LOCF and MMRM ; <span class="chemical">asenapine</span> at 5 mg BID was superior to placebo on the negative subscale with MMRM and on the general psychopathology subscale with LOCF and MMRM . 