Planar Differential Mobility Analyzer with a Resolving Power of 110.

Planar differential mobility analyzers (DMAs) have previously achieved resolving powers of 60-80 in air or N2 at the mobility of the tetraheptylammonium ion (THA+, ∼0.97 cm2/V/s). For unclear reasons, this performance is considerably below the theoretical limit. In this work, a performance close to this ideal limit is attained in SEADM's P5 DMA via improved flow laminarization, under otherwise the same flow conditions as in prior work. The new laminarizer remains effective at unusually large gas velocities (reached with two blowers in series), yielding a resolving power of 110. The selectivity of the improved DMA combined with a mass spectrometer was assessed by the analysis of a real sample of extra virgin olive oil.