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: Biochemically , an increase in alkaline phosphatases was noted in 5 of 8 cases ( 63 % ) , and the greatest increases were seen in those who had elevated levels prior to treatment .
### Output Text:
Biochemically , an increase in alkaline phosphatases was noted in 5 of 8 cases ( 63 % ) , and the greatest increases were seen in those who had elevated levels prior to treatment . 