MassSpecSettings_FindFeatures_xcms3_centwave
Source:R/class_S3_MassSpecSettings.R
MassSpecSettings_FindFeatures_xcms3_centwave.Rd
Settings for finding features (i.e., chromatographic peaks) in mzML/mzXML files using the package xcms (version 3) with the algorithm centWave. The function uses the package patRoon in the background.
Arguments
- ppm
numeric(1) defining the maximal tolerated m/z deviation in consecutive scans in parts per million (ppm) for the initial ROI definition.
- peakwidth
numeric(2) with the expected approximate feature width in chromatographic space. Given as a range (min, max) in seconds.
- snthresh
numeric(1) defining the signal to noise ratio cutoff.
- prefilter
numeric(2): c(k, I) specifying the prefilter step for the first analysis step (ROI detection). Mass traces are only retained if they contain at least k peaks with intensity >= I.
- mzCenterFun
Name of the function to calculate the m/z center of the chromatographic peak (feature). Allowed are: "wMean": intensity weighted mean of the peak's m/z values, "mean": mean of the peak's m/z values, "apex": use the m/z value at the peak apex, "wMeanApex3": intensity weighted mean of the m/z value at the peak apex and the m/z values left and right of it and "meanApex3": mean of the m/z value of the peak apex and the m/z values left and right of it.
- integrate
Integration method. For integrate = 1 peak limits are found through descent on the mexican hat filtered data, for integrate = 2 the descent is done on the real data. The latter method is more accurate but prone to noise, while the former is more robust, but less exact.
- mzdiff
numeric(1) representing the minimum difference in m/z dimension required for peaks with overlapping retention times; can be negative to allow overlap. During peak post-processing, peaks defined to be overlapping are reduced to the one peak with the largest signal.
- fitgauss
logical(1) whether or not a Gaussian should be fitted to each peak. This affects mostly the retention time position of the peak.
- noise
numeric(1) allowing to set a minimum intensity required for centroids to be considered in the first analysis step (centroids with intensity < noise are omitted from ROI detection).
- verboseColumns
logical(1) whether additional peak meta data columns should be returned.
- firstBaselineCheck
logical(1). If TRUE continuous data within regions of interest is checked to be above the first baseline.
- extendLengthMSW
Option to force centWave to use all scales when running centWave rather than truncating with the EIC length. Uses the "open" method to extend the EIC to a integer base-2 length prior to being passed to convolve rather than the default "reflect" method. See https://github.com/sneumann/xcms/issues/445 for more information.
Value
A ProcessingSettings S3 class object with subclass MassSpecSettings_FindFeatures_xcms3_centwave.
Details
See the findFeaturesXCMS3 function from the patRoon package for more information and requirements.
References
Helmus R, ter Laak TL, van Wezel AP, de Voogt P, Schymanski EL (2021). “patRoon: open source software platform for environmental mass spectrometry based non-target screening.” Journal of Cheminformatics, 13(1). doi:10.1186/s13321-020-00477-w .
Helmus R, van de Velde B, Brunner AM, ter Laak TL, van Wezel AP, Schymanski EL (2022). “patRoon 2.0: Improved non-target analysis workflows including automated transformation product screening.” Journal of Open Source Software, 7(71), 4029. doi:10.21105/joss.04029 .
Smith, C.A., Want, E.J., O'Maille, G., Abagyan,R., Siuzdak, G. (2006). “XCMS: Processing mass spectrometry data for metabolite profiling using nonlinear peak alignment, matching and identification.” Analytical Chemistry, 78, 779--787.
Tautenhahn R, Boettcher C, Neumann S (2008). “Highly sensitive feature detection for high resolution LC/MS.” BMC Bioinformatics, 9, 504.
Benton HP, Want EJ, Ebbels TMD (2010). “Correction of mass calibration gaps in liquid chromatography-mass spectrometry metabolomics data.” BIOINFORMATICS, 26, 2488.