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: Coronary spasm was induced by intracoronary injection of acetylcholine , and no fixed coronary artery stenosis was documented on angiograms in all patients .
### Output Text:
Coronary spasm was induced by intracoronary injection of <span class="chemical">acetylcholine</span> , and no fixed coronary artery stenosis was documented on angiograms in all patients . 