High-dynamic range scans (adjusting injection times)
Methods for acquiring mass spectral data of a sample across at least a portion of an m/z range comprise receiving mass spectral data across the m/z range and partitioning the m/z range into one or more sets of m/z sub-ranges, each set comprising one or more m/z sub-ranges, by dividing the m/z range into a plurality of m/z bins, determining an indication of ion abundance for each m/z bin, based on the mass spectral data, and forming an m/z sub-range of the one or more sets of m/z sub-ranges by assigning m/z bins having ion abundances that correspond to at least a threshold degree to the formed m/z sub-range. A mass analysis is performed on the sample for each set of m/z sub-ranges, thereby acquiring one or more partial mass spectral data sets.
1 . A method for acquiring mass spectral data of a sample across at least a portion of an m/z range, the m/z range comprising a set of one or more m/z sub-ranges, the method comprising:
determining an initial distribution of injection times comprising an initial injection time for each m/z sub-range of the set of one or more m/z sub-ranges;
based on determining that a total time of the initial distribution of injection times exceeds a total available injection time for acquiring the mass spectral data, determining an adjusted distribution of injection times comprising an adjusted injection time for each m/z sub-range; and
performing mass analysis on each m/z sub-range according to the adjusted distribution of injection times, so as to obtain a partial mass spectral data set;
wherein determining the adjusted distribution of injection times comprises reducing at least one of the initial injection times for a respective m/z sub-range, such that a total time of the adjusted distribution of injection times for the set of one or more m/z sub-ranges is no greater than the total available injection time for acquiring the mass spectral data.
2 . The method of claim 1 , wherein determining the adjusted distribution of injection times comprises reducing one or more relatively long initial injection times by a greater extent than one or more relatively short initial injection times.
3 . The method of claim 2 , wherein determining the adjusted distribution of injection times comprises reducing at least one, and preferably each, initial injection time that exceeds a threshold injection time.
4 . The method of claim 3 , wherein determining the adjusted distribution of injection times comprises reducing a plurality of initial injection times that exceed a threshold injection time by a scaling factor.
5 . The method of claim 4 , wherein determining the adjusted distribution of injection times comprises setting the threshold injection time as the adjusted injection time for each m/z sub-range for which the initial injection time reduced by the scaling factor is less than the threshold injection time.
6 . The method of claim 5 , wherein determining the adjusted distribution of injection times comprises:
determining a total spare injection time by summing, for each m/z sub-range for which the initial injection time is less than the threshold injection time, a difference between the initial injection time and the threshold injection time; and
setting an adjusted injection time for one or more m/z sub-ranges for which the initial injection time is greater than the threshold injection time, by distributing the total spare injection, thereby increasing the initial injection times for the one or more m/z sub-ranges for which the initial injection time is greater than the threshold injection time.
7 . The method of claim 6 , wherein determining the adjusted distribution of injection times comprises:
determining a sum, sum_exceeding, of each initial injection time that exceeds the threshold injection time, wherein the threshold injection time is IT Thr ;
determining a sum, sum_remaining, by subtracting each initial injection time that is less than or equal to IT Thr from the total available injection time;
processing each initial injection time that exceeds the threshold injection time in ascending order by iteratively:
calculating
an
adjusted
injection
time
,
new_IT
,
from
a
respective
initial
injection
time
,
old_IT
,
by
calculating
new_IT
=
max
(
IT
Thr
,
sum_remaining
sum_exceeding
*
old_IT
)
;
decreasing
sum_exceeding
by
old_IT
;
and
decreasing
sum_remaining
by
new_IT
.
8 . The method of claim 7 , wherein the threshold injection time is equal to the total available injection time divided equally between the one or more m/z sub-ranges.
9 . The method of claim 1 , further comprising:
receiving an indication that an m/z sub-range is an m/z sub-range of interest; and
setting a relatively high adjusted injection time for the m/z sub-range of interest.
10 . The method of claim 1 , wherein determining the adjusted distribution of injection times comprises reducing the initial injection times for each respective m/z sub-range.
11 . The method of claim 1 , wherein determining the adjusted distribution of injection times comprises reducing the initial injection times for each respective m/z sub-range by a scaling factor.
12 . The method of claim 1 , wherein determining the initial distribution of injection times comprises determining an initial injection time for each m/z sub-range based on an automatic gain control (AGC) algorithm.
13 . The method of claim 1 , wherein determining the adjusted distribution of injection times comprises adjusting the initial injection time for an m/z sub-range based on an indication of ion abundance for the respective m/z sub-range.
14 . The method of claim 13 , wherein determining the adjusted distribution of injection times comprises reducing the initial injection time for an m/z sub-range based on an indication that the ion abundance for the respective m/z sub-range is substantially caused by a single m/z peak.
15 . The method of claim 1 , wherein:
each set of m/z sub-ranges comprises a plurality of m/z sub-ranges and wherein each m/z sub-range in a given set of m/z sub-ranges at least partially overlaps an m/z sub-range of a different set of m/z sub-ranges.
16 . The method of claim 1 , further comprising performing mass analysis on one or more m/z sub-ranges of a respective set using different ion optics settings.
17 . The method of claim 1 , wherein each mass analysis is a MS 1 mass analysis.
18 . The method of claim 1 , wherein the m/z sub-ranges of each of the sets of m/z sub-ranges collectively span the m/z range.
19 . The method of claim 1 , further comprising receiving the sample from a chromatograph, preferably comprising repeating the method of any preceding claim one or more times on one or more samples obtained from the chromatograph to obtain time-dependent mass spectral data for the sample.
20 . A method for acquiring mass spectral data of a sample across at least a portion of an m/z range, the method comprising:
obtaining a plurality of partial mass spectral data sets using the method of claim 1 ; and
combining the plurality of partial mass spectral data sets into a single mass spectral data set.
21 . The method of claim 20 , wherein combining the plurality of partial mass spectral data sets comprises:
determining an end-m/z value that is within an intersection of a first m/z sub-range of the first set of m/z sub ranges and a second m/z sub-range of the second set of m/z sub ranges; and
including in the single mass spectral data set:
mass spectral data from between: the end-m/z value; and an endpoint of the first m/z sub-range; and
mass spectral data from between: the end-m/z value; and an endpoint of the second m/z sub-range;
preferably wherein:
the method comprises determining the end-m/z value based on a distribution of isotopes in the first and/or the second m/z sub-ranges; and/or
the intersection of the first m/z sub-range and the second m/z sub-range includes at least a portion of a relatively high transmission region of a first response profile and at least a portion of a relatively high transmission region of a second response profile.
22 . The method of claim 21 , comprising:
determining which of the first m/z sub-range and the second m/z sub-range is associated with a higher ion abundance; and wherein combining the plurality of partial mass spectral data sets into a single mass spectral data set comprises including in the single mass spectral data set the mass spectral data from the one of the first m/z sub-range and the second m/z sub-range that is associated with the higher ion abundance; and/or
determining which of the first m/z sub-range and the second m/z sub-range is associated with a higher signal-to-noise ratio; and wherein combining the plurality of partial mass spectral data sets into a single mass spectral data set comprises including in the single mass spectral data set the mass spectral data from the one of the first m/z sub-range and the second m/z sub-range that is associated with the higher signal-to-noise ratio.
23 . A mass spectrometry system comprising a mass analyser, a processor and one or more mass filters, configured to perform the method of claim 1 .
24 . A computer program comprising processor-executable instructions that, when executed by a processor of a mass spectrometry system that includes a mass analyser, the processor, and one or more mass filters, cause the mass spectrometry system to perform the method of claim 1 .
25 . A computer-readable medium having stored thereon processor-executable instructions for performing the method of claim 1 .