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: A flurothyl ether seizure screening technique was used to evaluate seizure susceptibility in adult mice that received neonatal injections of MSG ( 4 mg / g and 1 mg / g ) .
### Output Text:
A <span class="chemical">flurothyl</span> <span class="chemical">ether</span> seizure screening technique was used to evaluate seizure susceptibility in adult mice that received neonatal injections of <span class="chemical">MSG</span> ( 4 mg / g and 1 mg / g ) . 