Granted Patent B2

US 7,638,764 · App. 12/023,873 · Granted Dec 29, 2009

Abstract

Claims (28)

1. A method for reducing background noise in a mass spectrum, the method comprising the following steps:

(a) obtaining an original mass spectrum;

(b) determining a noise mass spectrum corresponding to background noise in the original mass spectrum;

(c) determining a corrected mass spectrum by subtracting the noise mass spectrum from the original mass spectrum; and

(d) wherein step (b) comprises the steps of:

A) effecting a transformation of the original mass spectrum into the frequency domain to obtain an original frequency spectrum;

B) identifying at least one dominant frequency in the original frequency spectrum;

C) generating a noise frequency spectrum by selectively filtering for said at least one dominant frequency; and

D) determining the noise mass spectrum by effecting a transformation of the noise frequency spectrum into the mass domain.

2. The method as claimed in claim 1 , wherein the original mass spectrum comprises a plurality of original intensity data points and wherein the noise mass spectrum comprises a plurality of noise intensity data points such that each noise intensity data point correlates to an original intensity data point, step (b) of the method further comprising the following step:

E) for each correlated pair of original and noise intensity data points:

(i) determining the minimum value; and

(ii) modifying the noise mass spectrum by making the noise intensity data point equal to the minimum value.

3. A spectrometer comprising a computer configured to carry out the method of claim 2 .

4. The method as claimed in claim 3 , step (b) further comprising the following steps:

F) effecting a transformation of the noise mass spectrum modified in step (E) into the frequency domain to obtain a noise frequency spectrum;

G) identifying at least one dominant frequency in the noise frequency spectrum;

H) modifying the noise frequency spectrum by selectively filtering for said at least one dominant frequency; and

I) determining the noise mass spectrum by effecting a transformation of the noise frequency spectrum into the mass domain.

5. The method as claimed in claim 4 , step (b) further comprising the following step:

J) repeating step (E) utilizing the noise mass spectrum determined in step (I).

6. The method as claimed in claim 5 , further comprising repeating steps (F) through (J) inclusively.

7. The method as claimed in claim 6 , further comprising the step of segmenting the original mass spectrum into a plurality of initial windows prior to step A, and separately effecting steps A through D inclusive for each initial window.

8. The method as claimed in claim 7 , further comprises the step of segmenting the noise mass spectrum into a plurality of subsequent windows prior to step F, and separately effecting steps F through I inclusive for each subsequent window.

9. The method as claimed in claim 8 , wherein the subsequent windows are configured such that no subsequent window is coextensive with any initial window.

10. The method as claimed in claim 9 , further comprising the step of subsequent to step J, for each repeat of steps G through J, segmenting the noise mass spectrum into a plurality of new windows prior to step G, and separately effecting steps G through J inclusive for each new window, and wherein the new windows are configured such that no new window is coextensive with any subsequent window.

11. A computer system configured to carry out the method of claim 1 .

12. A storage medium comprising a program configured to cause a computer system to carry out the method of claim 1 .

Assignments (10)