# US 2014/0151541 A1 · Electrokinetically Controlled Calibrant Delivery

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- Number: US 2014/0151541 A1
- Document ID: US20140151541A1
- Status: Published application
- Kind: A1
- Application number: 14/004,236
- Filed: 2012-03-08
- Published: 2014-06-05
- Earliest claimed: 2011-03-11
- Assignees: Waters Technologies Corporation
- Inventors: Geoff C. Gerhardt; Keith Fadgen
- Web page: https://patentgrep.com/patent/US20140151541A1

## CPC

- H01J 49/0009: {Calibration of the apparatus}
- H01J 49/00: Particle spectrometers or separator tubes
- H01J 49/04: Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

An electrokinetic pump can be used to deliver calibrant (“lock mass”) ions to a mass spectrometer for calibration of a mass spectrometry system. Electrokinetically controlled calibrant delivery can help to eliminate the need for the more cumbersome mechanisms that are often used for ion delivery. In addition, electrokinetically controlled calibrant delivery can provide for a more user-friendly system in which a calibrant solution can be packaged into a disposable cartridge. Furthermore, when implemented in a microfluidic format, electrokinetically controlled calibrant delivery can be coupled with an electrokinetically controlled separation system, such as capillary electrophoresis (CE), to allow efficient solid-state switching between analytical and calibrant sprays.

## Claims

### Claim 1

A method comprising:
actuating an electrokinetic pump and thereby providing an electroosmotic flow of a calibrant solution from a calibrant solution source to an electrospray ionization emitter such that a plume of calibrant ions is emitted from the electrospray ionization emitter toward an inlet orifice of a mass spectrometer.

### Claim 2 (depends on 1)

The method of claim 1, wherein actuating the electrokinetic pump comprises applying a high voltage to the electrokinetic pump.

### Claim 3 (depends on 2)

The method of claim 2, wherein the high voltage is about +100 volts to about +10 KV

### Claim 4 (depends on 2)

The method of claim 2, further comprising holding a source of calibrant solution at ground potential.

### Claim 5 (depends on 1)

The method claim 1, wherein actuating the electrokinetic pump comprises applying a high voltage to the electrokinetic pump for a plurality of discrete time intervals.

### Claim 6 (depends on 1)

The method of claim 1, wherein actuating the electrokinetic pump comprises alternating a voltage applied to the electrokinetic pump.

### Claim 7 (depends on 6)

The method of claim 6, wherein the applied voltage is alternated between an off state of about 0 kV and an on state of about +100 volts to about +10 kV.

### Claim 8 (depends on 1)

The method of claim 1, wherein the calibrant solution source comprises a reservoir operably connected to the electrokinetic pump.

### Claim 9 (depends on 1)

The method of claim 1, further comprising positioning a tip of the electrospray ionization emitter, relative to an inlet orifice of the mass spectrometer, such that a signal within 50% of optimal is achieved on the mass spectrometer.

### Claim 10 (depends on 1)

The method of claim 1, further comprising positioning a tip of the electrospray ionization emitter, relative to an inlet orifice of the mass spectrometer, such that an optimal signal is achieved on the mass spectrometer.

### Claim 11 (depends on 1)

The method of claim 1, wherein the mass spectrometer is a time-of-flight (TOF) mass spectrometer.

### Claim 12

A method comprising
applying a voltage to a microfluidic device and thereby delivering calibrant ions toward an inlet orifice of a mass spectrometer.

### Claim 13 (depends on 12)

The method of claim 12, wherein the microfluidic device comprises an electrokinetic pump, and wherein the applied voltage actuates the electrokinetic pump thereby delivering calibrant ions toward a mass spectrometer.

### Claim 14 (depends on 13)

The method of claim 13, wherein the electrokinetic pump is actuatable to provide an electroosmotic flow of a calibrant solution from a calibrant solution source to an electrospray ionization emitter such that a plume of the calibrant ions is emitted from the electrospray ionization emitter toward the inlet orifice of the mass spectrometer.

### Claim 15 (depends on 14)

The method of claim 14, wherein the calibrant solution source is a reservoir mounted to the microfluidic device.

### Claim 16 (depends on 13)

The method of claim 13, wherein the electrokinetic pump is operably connected to a calibrant electrospray ionization emitter, and wherein actuation of the electrokinetic pump causes the calibrant electrospray ionization emitter to emit a plume of the calibrant ions.

### Claim 17 (depends on 12)

The method of claim 12, wherein the mass spectrometer is a time-of-flight (TOF) mass spectrometer.