Fluoride content is least –
High-Yield Explanation
Amongst the given options isoflurane produces minimum fluoride.
Methoxyflurane → 50 m
Sevoflurane → 30 - 50 m
Enflurane → 20 - 25 in
Isoflurane → 4 - 8 m
Halothane → Only in anaerobic conditions
Desflurane → Zero