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: A 49 - year - old woman was transferred to our department because of quadriparesis , lancinating pain , sensory loss , and paresthesia of the distal limbs .
### Output Text:
A 49 - year - old woman was transferred to our department because of quadriparesis , lancinating pain , sensory loss , and paresthesia of the distal limbs . 