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: Although the AE RBCs from an individual not taking dapsone had increased incubated Heinz body formation , the GSH content and GSH stability were normal .
### Output Text:
Although the AE RBCs from an individual not taking <span class="chemical">dapsone</span> had increased incubated Heinz body formation , the <span class="chemical">GSH</span> content and <span class="chemical">GSH</span> stability were normal . 