Solid phase extraction with capillary electrophoresis

Patent metadata

Field	Value
Publication number	US-9728387-B2
Application number	US-201615079541-A
Country	US
Kind code	B2
Filing date	Mar 24, 2016
Priority date	Oct 20, 2015
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

Methods, systems and devices that provide fluid devices with at least one SPE bed adjacent (upstream of) a separation channel which may be in communication with an inlet of a Mass Spectrometer. The fluid device can be configured to operate using independently applied pressures to a BGE reservoir and a sample reservoir for pressure-driven injection that can inject a discrete sample plug into a separation channel that does not require voltage applied to the sample reservoir and can allow for in-channel focusing methods to be used. The methods, systems and devices are particularly suitable for use with a mass spectrometer but optical or other electronic detectors may also be used with the fluidic devices.

First claim

That which is claimed is:

1. A method of sample processing, comprising:
providing a fluidic device with at least one microfluidic or nanofluidic separation channel in fluid communication with a background electrolyte (BGE) reservoir, and a nanofluidic or microfluidic sample channel in fluid communication with the separation channel, wherein the sample channel comprises at least one solid phase extraction (SPE) bed;
flowing a sample through the sample channel, across the at least one SPE bed, and into the separation channel;
electrophoretically separating an analyte component from the sample in the separation channel; and
performing at least one of:
(a) electrospraying the analyte component from at least one emitter in fluid communication with the separation channel toward at least one of a collection device or an inlet of a mass spectrometer; and
(b) detecting a signal corresponding to the analyte component in, or emerging from, the separation channel,

wherein the method further comprises:
flowing an ion-pairing agent across the at least one SPE bed in advance of, or together with, the sample;
rinsing the ion pairing agent from the sample channel into a waste channel in fluid communication with the sample channel; and
after rinsing the ion pairing agent from the sample channel, flowing an elution fluid in the sample channel before or during the electrophoretic separation.

2. The method of claim 1 , further comprising pre-concentrating the sample prior to the electrophoretic separation.

3. The method of claim 2 , wherein the sample is an ionized sample, and wherein the flowing comprises:
flowing the ionized sample in the separation channel in a first direction following a leading electrolyte with a first mobility, and in advance of a trailing electrolyte with a second mobility lower than the first mobility, so that if the sample comprises multiple components, a component of the sample having a highest mobility flows directly behind the leading electrolyte, and a component of the sample having a lowest mobility flows directly in advance of the trailing electrolyte, in the first direction.

4. The method of claim 1 , wherein the sample is flowed across the at least one SPE bed and into the separation channel without directing the sample through a valve, and wherein the electrophoretically separating the analyte component comprises applying an electric field to the fluidic device so that at least a component of the electric field is parallel to an axial direction of a portion of the separation channel.

5. The method of claim 4 , wherein the applying the electric field comprises applying an electrical potential difference between a first position in the BGE reservoir and a second position downstream from the first position, wherein the second position is located in the separation channel or in a pump channel or in a reservoir in fluid communication with one or both of the separation or the pump channel of the fluidic device.

6. The method of claim 1 , wherein the ion-pairing agent comprises trifluoroacetic acid (TFA).

7. The method of claim 1 , further comprising, after flowing the sample through the sample channel and across the at least one SPE bed, flowing an elution fluid through the sample channel and across the at least one SPE bed.

8. The method of claim 1 , further comprising, prior to flowing the sample across the at least one SPE bed, pre-conditioning the SPE bed by flowing a pre-conditioning fluid across the at least one SPE bed and into a waste reservoir of the fluidic device.

9. The method of claim 1 , further comprising, prior to flowing the sample through the sample channel, forming the at least one SPE bed in the sample channel by flowing a SPE material into the sample channel.

10. The method of claim 9 , wherein the SPE bed comprises a length, measured along a flow direction defined by the sample channel, of between 100 μm and 1000 μm, and a volume of between about 50 pL to about 10 nL.

11. The method of claim 1 , further comprising using a blocking member to at least partially occlude the sample channel, wherein the blocking member is positioned adjacent to an end of the at least one SPE bed that is closest to the separation channel.

12. The method of claim 1 , further comprising:
flowing the sample through the sample channel by pressurizing sealed headspaces of the BGE reservoir, a waste reservoir, and a sample reservoir comprising the sample,
wherein the BGE reservoir, the waste reservoir, and the sample reservoir are each in fluid communication with the separation channel; and
wherein the sample is flowed through the sample channel without applying a voltage to the sample reservoir, to the BGE reservoir, or to the waste reservoir and/or with no electric potential gradient in any of the sample channel, the BGE channel and the waste channel.

13. A method of sample processing, comprising:
providing a fluidic device with a microfluidic or nanofluidic separation channel in fluid communication with a background electrolyte (BGE) reservoir, and a nanofluidic or microfluidic sample channel in fluid communication with the separation channel, wherein the sample channel comprises at least one solid phase extraction (SPE) bed, and wherein a leading end of the at least one SPE bed is positioned at a distance of between 50 μm and 500 μm from the separation channel;
flowing a sample through the sample channel, across the at least one SPE bed, and into the separation channel;
electrophoretically separating an analyte component from the sample in the separation channel; and
performing at least one of:
(a) electrospraying the analyte component from at least one emitter in fluid communication with the separation channel toward at least one of a collection device or an inlet of a mass spectrometer; and
(b) detecting a signal corresponding to the analyte component in, or emerging from, the separation channel,

wherein the method further comprises applying hydrodynamic pressure to cause the sample to flow through the sample channel, across the at least one SPE bed, and into the separation channel.

14. A method of sample processing, comprising:
providing a fluidic device with at least one microfluidic or nanofluidic separation channel in fluid communication with a background electrolyte (BGE) reservoir, and a nanofluidic or microfluidic sample channel in fluid communication with the separation channel, wherein the sample channel comprises at least one solid phase extraction (SPE) bed;
applying hydrodynamic pressure to cause the sample to flow through the sample channel, across the at least one SPE bed, and into the separation channel;
electrophoretically separating an analyte component from the sample in the separation channel; and
performing at least one of:
(a) electrospraying the analyte component from at least one emitter in fluid communication with the separation channel toward at least one of a collection device or an inlet of a mass spectrometer; and
(b) detecting a signal corresponding to the analyte component in, or emerging from, the separation channel,

wherein applying the hydrodynamic pressure comprises:
(a) first, concurrently applying pressures of between 0.1 pounds per square inch (psi) and 30 psi to each of a sealed headspace of a waste reservoir of the fluidic device and a sealed headspace of a sample reservoir of the fluidic device, wherein a pressure applied to the sealed headspace of the waste reservoir is less than a pressure applied to the sealed headspace of the sample reservoir;
(b) second, concurrently applying pressures to a sealed headspace of the BGE reservoir and to the sealed headspac

Assignees

• Univ North Carolina Chapel Hill

Inventors

• Mellors John Scott
• Black William A
• Ramsey John Michael

Classifications

• H01J49/165

  Electrospray ionisation · CPC title

• G01N27/44743

  Introducing samples · CPC title

• G01N27/4473

  by electric means · CPC title

• H01J49/0459 Primary

  for solid samples · CPC title

• G01N27/44791 Primary

  Microapparatus (sample containers with integrated microfluidic structures B01L3/5027) · CPC title