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: Total fasciculation scores in the 30 - mg bolus group and the 5 - mg s - 1 and 20 - mg s - 1 infusion groups were not significantly different .
### Output Text:
Total fasciculation scores in the 30 - mg bolus group and the 5 - mg s - 1 and 20 - mg s - 1 infusion groups were not significantly different . 