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: Cibenzoline suppressed all the arrhythmias , and the minimum effective plasma concentrations for arrhythmias induced by 24 - h coronary ligation , 48 - h coronary ligation , digitalis , and adrenaline were 1 . 9 + / - 0 . 9 ( by 8 mg / kg i . v . ) , 1 . 6 + / - 0 . 5 ( by 8 mg / kg i . v . ) , 0 . 6 + / - 0 . 2 ( by 2 mg / kg i . v . ) , and 3 . 5 + / - 1 . 3 ( by 5 mg / kg i . v . ) micrograms / ml , respectively ( mean + / - SDM , n = 6 - 7 ) .
### Output Text:
<span class="chemical">Cibenzoline</span> suppressed all the arrhythmias , and the minimum effective plasma concentrations for arrhythmias induced by 24 - h coronary ligation , 48 - h coronary ligation , <span class="chemical">digitalis</span> , and <span class="chemical">adrenaline</span> were 1 . 9 + / - 0 . 9 ( by 8 mg / kg i . v . ) , 1 . 6 + / - 0 . 5 ( by 8 mg / kg i . v . ) , 0 . 6 + / - 0 . 2 ( by 2 mg / kg i . v . ) , and 3 . 5 + / - 1 . 3 ( by 5 mg / kg i . v . ) micrograms / ml , respectively ( mean + / - SDM , n = 6 - 7 ) . 