MassSpectator online calculator
MassSpectator is a mathematical method that locates, and calculates
the area beneath, peaks from mass spectra using only reproducible
mathematical operations and no user-selected parameters. It makes no
assumptions about peak shape and requires no smoothing or
preprocessing of the data. However, to facilitate this approach the
method requires a background spectrum to be taken in order to
determine inherent instrument noise. The background spectrum is taken
under the same conditions as the data with the only difference being
the absence of analyte.
The algorithm is based on a time-series segmentation routine that
reduces the data set to groups of three strategic points where each
group defines the beginning, center, and ending of each peak located.
The peak areas are found from the strategic points using a simple
polygonal area calculation routine. Peaks with statistically
insignificant height or area are then discarded. The output file
format contains one line per peak found. Each line consists of seven
entries: the peak beginning x and y coordinates, the peak center x and
y coordinates, the peak ending x and y coordinates and the area
(2+2+2+1=7 entries per line).
The input files must be simple ASCII text files of two columns: one
for mass and one for ion intensity. They can be tab, space, or comma
delimited and must be of the same length. The spacing between mass
values does not need to be equal (i.e. time-of-flight data converted
to mass with its consequent square-root point spacing is OK); however,
the mass values need to be monotonically increasing. Be sure to use a
sufficient number of significant digits in the ion intensity. Some
software packages will default to a number of significant digits that
is too small for accurate calculation of background noise. Six
significant figures should suffice; eight would be better.
MassSpectator is a collaborative project between the
Polymers Division of
the Materials Science and Engineering
Laboratory and the Mathematical and
Computational Sciences Division of the
Information Technology Laboratory,
both of NIST.
Details of this method can be found in the following two papers:
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DISCLAIMER: Employees of the Federal Government in the course of their
official duties developed this software at the National Institute of
Standards and Technology. Pursuant to title 17 Section 105 of the
United States Code this software is not subject to copyright
protection and is in the public domain. MassSpectator is an
experimental system. NIST assumes no responsibility whatsoever for its
use by other parties, and makes no guarantees, expressed or implied,
about its quality, reliability, or any other characteristic. We would
appreciate acknowledgement if the software is used.