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Electrospray Ionization (ESI) Mass Spectrometry

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Colloidal precipitates

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Related Experiment Video

Updated: Jul 18, 2026

Glass-Based Devices to Generate Drops and Emulsions

Glass-Based Devices to Generate Drops and Emulsions

Published on: April 5, 2022

Negative droplets from positive electrospray.

Joshua T Maze¹, Thaddeus C Jones, Martin F Jarrold

¹Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.

The Journal of Physical Chemistry. A

|November 17, 2006

Summary

Electrosprayed water droplets were measured for charge and velocity. Surprisingly, a small fraction of positively biased electrosprayed droplets were negatively charged, possibly due to bipolar fission.

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Last Updated: Jul 18, 2026

Glass-Based Devices to Generate Drops and Emulsions

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Area of Science:

Physics
Chemistry

Background:

Electrospraying is a technique used to generate charged droplets.
Understanding droplet charge is crucial for controlling applications.

Purpose of the Study:

To investigate the charge distribution of electrosprayed water droplets.
To explore the reasons behind the unexpected observation of negatively charged droplets.

Main Methods:

Utilized image charge detection to measure individual droplet charge and velocity.
Applied a positive bias to the electrospray needle.

Main Results:

The majority of electrosprayed water droplets were positively charged, as expected.
A small but significant fraction of droplets unexpectedly exhibited negative charges.

Conclusions:

The presence of negatively charged droplets challenges conventional expectations.
Bipolar fission is proposed as a plausible mechanism, where a small negative droplet forms between two larger positive droplets, facilitating fission.