APCI interface for LC- and SEC-MS analysis of synthetic polymers: advantages and limits

The main advantage of the APCI interface for the LC-MS analysis of synthetic polymers resides in its compatibility with the main chromatographic modes: reversed-phase liquid chromatography, normal-phase liquid chromatography, and size exclusion chromatography in organic phase, with the usual flow rates. Moreover, APCI can be used in positive or negative modes. Representative applications are described to highlight benefits and limitations of the LC-APCI-MS technique with the analysis of industrial polymers up to molecular masses of 5 kDa: polyethers; polysiloxanes; and copolymers of siloxanes. Results are discussed in regard to those obtained by more classical techniques: SEC and MALDI-MS. The use of an APCI interface in LC-MS and SEC-MS coupling applied to synthetic polymers is efficient up to 2000-4500 Da. The main drawback of the APCI interface is the in-source decomposition that is observed above m/z = 2000-3000 and can induce an underestimation of average molecular weights. However, APCI allows detection on a wide range of polarity of sample/solvent and appears to be complementary to ESI.