FD is another technique used for involatile compounds. FD works best for compounds of low polarity, and thus complements FAB. FD uses the same emitter wires used in FI, but the samples are loaded directly on the wire by dipping into a solution of the sample. The sample for FD must be soluble in some solvent (usually 2 mg in 100 microliter).

Low resolution FD Instrument: 70-VSE Sample size: 1-2 mg

Spectra are obtained at increasing emitter heating current and is reported in milliamps on each spectrum. You must indicate a solvent on your sample submission form, since a solution of your compound is deposited on the emitter wire in FD.