Method for evaluating data from mass spectrometry, mass spectrometry method, and maldi-tof mass spectrometer

Patent metadata

Field	Value
Publication number	US-2019257839-A1
Application number	US-201716342088-A
Country	US
Kind code	A1
Filing date	Sep 22, 2017
Priority date	Oct 17, 2016
Publication date	Aug 22, 2019
Grant date	—

Abstract

The invention relates to a method to evaluate mass spectrometry data for the analysis of peptides from biological samples, particularly MALDI-TOF mass spectrometry data, comprising the following steps:
a) provide expected mass defects; b) determine measured mass defects, i.e. the mass defects resulting from the mass spectrometry data; c) compare the measured mass defects with the expected mass defects.

First claim

1 . Method to evaluate mass spectrometry data for the analysis of peptides from biological samples, particularly MALDI-TOF mass spectrometry data, comprising the following steps:
a) provide expected mass defects; b) determine measured mass defects, i.e. the mass defects resulting from the mass spectrometry data; c) compare the measured mass defects with the expected mass defects.

2 . The method according to claim 1 , wherein the expected mass defects are calculated from
m N r p ,
where m N designates the nominal mass of a peptide.

3 . The method according to claim 1 , wherein the mass defect for a measured mass m is calculated from

m
-

floor


(

m

1
+

r
p

+
0.5

)

,

where the function floor(x) for an arbitrary x>0 designates the integer part of x.

4 . The method according to claim 1 , wherein the discrepancy δ P between the measured and the expected mass defect is calculated directly from the measured mass m as

δ
p



(
m
)

=

ϕ


(

m

1
+

r
p

+
0.5

)

-
0.5

where the function φ(x)=x−floor(x) designates the decimal places of x for any x>0.

5 . The method according to claim 1 , wherein the median of the measured mass defects is formed and compared with the expected mass defect in order to compare the measured mass defects with the expected mass defects over subintervals of a mass axis.

6 . The method according to claim 1 , wherein the measured values are corrected when the data are to be used further, i.e. depending on the deviation of the measured mass defects from the expected mass defects.

7 . The method according to claim 1 , wherein the measured mass defects are calculated for local maxima of the spectral intensities.

8 . Method to evaluate mass spectrometry data for the analysis of peptides from biological samples, particularly MALDI-TOF mass spectrometry data, comprising the following steps:
a) provide expected mass defects; b) determine measured mass defects, i.e. the mass defects resulting from the mass spectrometry data; c) determine the discrepancies between the measured mass defects and the expected mass defects; d) determine the variance of the discrepancies about their mean; e) compare the variance with a defined acceptable variance.

9 . The method according to claim 8 , wherein interquartile ranges of the ascertained discrepancies are determined over subintervals of the mass axis in order to determine a variance of the mass defect discrepancies, and the data are rejected as defective particularly when a limit value of the variance is exceeded.

10 . The method according to claim 8 , wherein an interval for acceptable variances is formed by limit values

d
p

1
,
2



(
m
)

=

±
μ



v


(
m
)

where

v


(
m
)

=

σ
P
2



(
m
)

+

Δ




m


(
m
)

2

12

and σ P (m N )=σ 0 +s P m N , where σ 0 ≈0.02 and s P ≈2.0×10 −5 ,
and Δm(m) designates the width of the m/z bins at the mass position m,
and m/z bins represent the intervals resulting from the discretization of the mass axis,
and μ>0 provides a scaling factor,
and that, in particular, the data are rejected as defective when the variance of the mass defect discrepancies are outside the interval thus specified.

11 . The method according to claim 8 , wherein the mass range with a recognizable peptide signal is determined as the totality of all the subintervals of the mass axis for which the quotient of the actual variance and the maximum permissible variance dp(m) does not exceed a specified threshold value t, and the data are rejected as defective when a limit value for the lower or upper limit of this mass range or its extent is exceeded or not reached.

12 . Mass spectrometric method for the analysis of peptides from biological samples, particularly by means of a MALDI TOF mass spectrometer, comprising the following steps:
a) carry out one or more mass spectrometric analyses on the biological sample and provide data which result from the mass spectrometric analyses; b) carry out the method according to claim 1 .

13 . Mass spectrometric method for dealing with an individual spec

Assignees

• Bruker Daltonik Gmbh

Inventors

• Boskamp Tobias

Classifications

• H01J49/0009

  Calibration of the apparatus · CPC title

• G01N33/6848 Primary

  Methods of protein analysis involving mass spectrometry · CPC title

• H01J49/0036

  Step by step routines describing the handling of the data generated during a measurement · CPC title

• G16B40/10

  Signal processing, e.g. from mass spectrometry [MS] or from PCR · CPC title