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: We report the case of a 35 - year - old patient suffering from schizo - affective disorder since the age of 19 years , treated by a combination of first - generation antipsychotics , zuclopenthixol ( 100 mg / day ) and lithium ( 1200 mg / day ) ( serum lithium = 0 . 85 mEq / l ) .
### Output Text:
We report the case of a 35 - year - old patient suffering from schizo - affective disorder since the age of 19 years , treated by a combination of first - generation antipsychotics , <span class="chemical">zuclopenthixol</span> ( 100 mg / day ) and <span class="chemical">lithium</span> ( 1200 mg / day ) ( serum <span class="chemical">lithium</span> = 0 . 85 mEq / l ) . 