Practice question

Ionization techniques are categorized as hard or soft based on extent of fragmentation induced. Hard ionization like electron ionization deposits abundant internal energy causing extensive bond cleavage. Soft methods preserve molecular ions. MALDI uses matrix buffer absorbing laser energy, producing intact singly charged ions. Fast atom bombardment bombards analyte in glycerol matrix with high-energy argon atoms, also yielding protonated molecules with little fragmentation, enabling analysis of polar peptides. Electrospray is also soft. Therefore, both MALDI and FAB qualify as soft ionization techniques, while electron ionization does not meet this gentle energy deposition criteria.