An atmospheric pressure ion lens to improve electrospray ionization at lowsolution flow-rates

The performance of a reduced flow-rate electrospray ion source is substanti ally improved by the addition of an atmospheric pressure ion lens near the tip of the tapered sprayer. The magnitude and stability of ion signals, det ected within a mass spectrometer, are significantly improved. In addition, the ion lens decreased the dependence of the ion signals on the sprayer pos ition. These benefits are believed to be due to an improvement in the shape of the equipotential lines near the tip of the electrospray ion source. Co pyright (C) 2001 John Wiley & Sons, Ltd.