mobilityTransform performs effective mobility scale transformation
of CE(-MS) data, which is used to overcome variations of the migration
times, caused by differences in the Electroosmotic Flow (EOF) between
In order to monitor the EOF and perform the transformation, neutral or
charged EOF markers are spiked into the sample before analysis. The
information of the EOF markers (migration time and effective mobility)
will be then used to perform the effective mobility transformation of
the migration time scale.
For the transformation, either one mobility marker or both can be used.
If a single marker is used, either a neutral EOF marker, or charged
marker with its corresponding mobilities (0 for the neutral marker) must
be provided, along with the applied voltage
U, and the total capillary
If two markers are used, both a neutral EOF marker and a charged marker
including their corresponding mobility must be provided.
Additionally, field ramping delays can be included by
tR, which will
result in more precise effective mobility values.
numeric vectors of migration
times as input,
mobilityTransform is a method that used different functions to convert
CE-MS data, depending on the input class. Following functions will be
applied depending on the input class:
`.transformNumeric`: performs effective mobility scale transformation of a `numeric` migration time vector as input. This can be used to transform a row of migration times or a single value. This function will return a `numeric` `.transformSpectra` performs effective mobility scale transformation of the migration time scale within a `Spectra` object. This function will return a `Spectra` object with effective mobility scale `.transformOnDiskMSnExp` performs effective mobility scale transformation of the migration time scale within an `OnDiskMSnExp` object. Since `OnDiskMSnExp` can store multiple files, it is also possible to perform the transformation of multiple files. Hence, `.transformOnDiskMSnExp` requires the `marker` `data.frame` to have an additional column "fileIdx" that stores the file Index of the migration time of all markers.
mobilityTransform(x, marker, tR = 0, U = numeric(), L = numeric())
The same class as the input class will be returned, i.e. if a
is used as input a
numeric that represents effective mobility will be
returned. If a
Spectra-Object is the input, also a
with transformed mobility scale will be returned. The same applies for
The respective unit for the effective mobility is mm^2 / (kV * min)
rtime <- c(10, 20, 30, 40, 50, 60, 70, 80, 90, 100) marker <- data.frame( markerID = c("marker1", "marker2"), rtime = c(20, 80), mobility = c(0, 2000) ) mobilityTransform(x = rtime, marker = marker)
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