Table 3.

FI, FD, and LIFDI in comparison to other ionization methods.

Polarity	FI	FD	LIFDI	EI	APCI	FAB	DART	ESI	MALDI
Positive ions	+	+	+	+	+	+	+	+	+
Negative ions	–	(+)1	–	–	+	+	+	+	+
Analyte property
Nonpolar M	+	+	+	+	(+)	+	(+)	–	(+)
Polar M	+	+	+	+	+	+	+	(+)	+
Highly polar M	(+)	+	+	(+)	+	+	+	+	+
Ionic CA	–	+	+	–	(+)	+	+	+	+
Volatile	+	–	–	+	+	–	+	–	–
Involatile	–	+	+	–	+	+	+	+	+
Air/water sensitive	+	–	+	(+)2	–	(+)2	–	(+)3	–
Other
GC-MS	+	–	(+)4	+	(+)5	–	–	–	–

¹Only selected instruments can do; rarely used.

²Special sample handling like glove box required.

³Restricted to ionic analytes in dry aprotic solvents.

⁴When LIFDI probe is used in FI mode.

⁵Special GC interface required.