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: Proteinase 3 - antineutrophil cytoplasmic antibody ( PR3 - ANCA ) titer was elevated at 183 ELISA units ( EU ) in sera ( normal range less than 10 EU ) , myeloperoxidase - ANCA was negative .
### Output Text:
Proteinase 3 - antineutrophil cytoplasmic antibody ( PR3 - ANCA ) titer was elevated at 183 ELISA units ( EU ) in sera ( normal range less than 10 EU ) , myeloperoxidase - ANCA was negative . 