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: Complications were observed in two patients : one had a left homonymous hemianopsia after pallidotomy and another one developed left hemiballistic movements 3 days after subthalamotomy which partly improved within 1 month with Valproate 1000 mg / day .
### Output Text:
Complications were observed in two patients : one had a left homonymous hemianopsia after pallidotomy and another one developed left hemiballistic movements 3 days after subthalamotomy which partly improved within 1 month with <span class="chemical">Valproate</span> 1000 mg / day . 