APLI –how it works

APLI is based on photon ionisation. In contrast to APPI (Atmospheric pressure Photo Ionisation), a two-step ionisation process is involved. This two-step ionisation leads to increased selectivity since only compounds with an electronically excited state of a rather long lifetime can be ionised by APLI. PAH compounds in particular fullfil this requirement.

Solvent molecules such as acetonitrile do not interact with the laser beam (in contrast to APPI), therefore the penetration depth of the beam is much higher than in case of APPI, resulting in enhanced sensitivity. Compared to APPI or dopant-asstisted APCI, the sensitivity of APLI is approximately 10-100 times better. Even difficult sample matrices such as olive pomace? oil can be analysed for PAH without compromise. APLI can be used for PAH analysis in combination with GC and LC.

Compared to other ionisation techniques, APLI has two mayor advantages:

• The spectra obtained with APLI are distinguished by a reduced base-line noise.
• The ionization efficiency for the various PAHs is generally orders of magnitude higher for APLI.