Integrated sample processing for electrospray ionization devices

A fluidic device, comprising:

• a separation channel formed in a substrate and comprising a first coating formed on a wall of the separation channel;
• a first electrode positioned so that when a fluid fills the separation channel, the first electrode contacts the fluid in the separation channel;
• a background channel formed in the substrate and connected to the separation channel at a junction;
• a second electrode positioned so that when a fluid fills the background channel, the second electrode contacts the fluid in the background channel;
• and
• an emitter connected to the separation channel,
• wherein the first coating is formed from a first coating material selected such that when a fluid comprising a target analyte and one or more non-target components in an electrolyte medium is introduced into the separation channel and further electrolyte medium is introduced into the background channel, the fluid in the separation channel has a first effective viscosity and the electrolyte medium in the background channel has a second effective viscosity different from the first effective viscosity;
• and
• wherein the device is configured to discharge the target analyte from the emitter and to prevent discharge of the one or more non-target components from the emitter when electrical potentials are applied to the first and second electrodes.

A method, comprising:

• disposing an electrolyte medium in a separation channel and in a background channel of a fluidic device in fluid communication with the separation channel, wherein the separation channel is configured so that an effective viscosity of the electrolyte medium in the separation channel is different from an effective viscosity of the electrolyte medium in the background channel;
• applying an electrical field across the electrolyte medium in the separation and background channels to cause electroosmotic flow of the electrolyte medium within the background and separation channels;
• transporting a target analyte from the separation channel to an emitter connected to the separation channel;
• and
• preventing transport of one or more non-target substances from the separation channel to the emitter.