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: The high image quality suggests that high contrast images can be obtained in humans and the 96 h stability makes it an ideal agent to detect , in patients , early cardiac infarction .
### Output Text:
The high image quality suggests that high contrast images can be obtained in humans and the 96 h stability makes it an ideal agent to detect , in patients , early cardiac infarction . 