Kc. Lewis et al., ELECTROSPRAY-CONDENSATION PARTICLE COUNTER - A MOLECULE-COUNTING LC-DETECTOR FOR MACROMOLECULES, Analytical chemistry, 66(14), 1994, pp. 2285-2292
A new detector for macromolecular separations is described. The detect
or counts individual macromolecules (molecular weights greater than ab
out 10 000) and reports counts per second. The chromatographic effluen
t is electrosprayed, neutralized, and swept to the detector by a strea
m of air. The detector is a condensation particle counter that detects
individual particles by light scattering from droplets condensed on t
he particles. When used as the detector for a size exclusion separatio
n of proteins, the detector has a linear range of 4 orders of magnitud
e with detection limits as low as 0.1 mu g/mL. The detector can be dir
ectly interfaced (no makeup flow) with effluent flows as low as 10 nL/
min. A Monte Carlo model based on size measurements of the electrospra
yed droplets correctly predicts the observed detector behavior.