# US 2015/0144784 A1 · Exponential Scan Mode for Quadrupole Mass Spectrometers to Generate Super-Resolved Mass Spectra

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- Number: US 2015/0144784 A1
- Document ID: US20150144784A1
- Status: Published application
- Kind: A1
- Application number: 14/565,345
- Filed: 2014-12-09
- Published: 2015-05-28
- Earliest claimed: 2012-11-30
- Assignees: Thermo Finnigan LLC
- Applicants: Thermo Finnigan LLC
- Inventors: Robert A. GROTHE, Jr.
- Web page: https://patentgrep.com/patent/US20150144784A1

## CPC

- H01J 49/4215: {Quadrupole mass filters (H01J49/4225 takes precedence)}
- H01J 49/0031: {Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence)}
- H01J 49/4225: {Multipole linear ion traps, e.g. quadrupoles, hexapoles}
- H01J 49/429: {Scanning an electric parameter, e.g. voltage amplitude or frequency}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A novel scanning method of a mass spectrometer apparatus is introduced so as to relate by simple time shifts, rather than time dilations, the component signal (“peak”) from each ion even to an arbitrary reference signal produced by a desired homogeneous population of ions. Such a method and system, as introduced herein, is enabled in a novel fashion by scanning exponentially the RF and DC voltages on a quadrupole mass filter versus time while maintaining the RF and DC in constant proportion to each other. In such a novel mode of operation, ion intensity as a function of time is the convolution of a fixed peak shape response with the underlying (unknown) distribution of discrete mass-to-charge ratios (mass spectrum). As a result, the mass distribution can be reconstructed by deconvolution, producing a mass spectrum with enhanced sensitivity and mass resolving power.

## Claims

### Claim 1

A mass spectrometer, comprising:
a quadrupole mass filter for mass selectively transmitting ions from an entrance end to an exit end, the quadrupole mass filter including:
four elongated electrodes arranged in parallel; and
a power supply, coupled to the electrodes, for applying a resolving DC voltage U and an RF voltage of amplitude V to the electrodes, the power supply being operated to temporally vary U and V during a scan period such that U and V both increase exponentially with time while the ratio of U to V is maintained constant; and
a detector, positioned to receive ions transmitted to the exit end of the quadrupole mass filter, for sensing ions and responsively generating a signal representative of the abundance of sensed ions.

### Claim 2 (depends on 1)

The mass spectrometer of claim 1, wherein the detector is an arrayed detector configured to measure the spatial distribution of ions within a detection plane.

### Claim 3 (depends on 1)

The mass spectrometer of claim 1, wherein the power supply is operated to cause multiple ion species having a range of mass-to-charge ratios within a transmission window to be transmitted to the exit end of the quadrupole mass filter at a specific timepoint.

### Claim 4 (depends on 1)

The mass spectrometer of claim 1, wherein the transmission window has a width of at least 10 Dalton (Da).

### Claim 5 (depends on 2)

The mass spectrometer of claim 2, wherein the detector is configured to acquire a time series of images, each image representing the spatial distribution of ions at a specific timepoint.

### Claim 6 (depends on 5)

The mass spectrometer of claim 5, further comprising a data processing system programmed to deconvolve data present in the images to generate a mass spectrum.

### Claim 7 (depends on 6)

The mass spectrometer of claim 6, wherein the data processing system is programmed to deconvolve data present in the images by computing cross-products with a set of reference signals, the reference signals each being representative of the measured or expected spatial distribution of a single ion species at a particular operating state of the quadrupole mass filter.

### Claim 8 (depends on 1)

The mass spectrometer of claim 1, further comprising a collision cell positioned upstream in an ion path of the quadrupole mass filter.

### Claim 9 (depends on 1)

The mass spectrometer of claim 1, further comprising a second quadrupole mass filter positioned upstream of the collision cell in the ion path.