Calculate neutral mass

mz2mass calculates the neutral mass from a given m/z value and adduct definition.

Custom adduct definitions can be passed to the adduct parameter in form of a data.frame. This data.frame is expected to have columns "mass_add" and "mass_multi" defining the additive and multiplicative part of the calculation. See adducts() for examples.

Usage

mz2mass(x, adduct = "[M+H]+")

Arguments

x

numeric m/z value for which the neutral mass shall be calculated.

adduct

either a character specifying the name(s) of the adduct(s) for which the m/z should be calculated or a data.frame with the adduct definition. See adductNames() for supported adduct names and the description for more information on the expected format if a data.frame is provided.

Value

numeric matrix with same number of rows than elements in x and number of columns being equal to the length of adduct (adduct names are used as column names. Each column thus represents the neutral mass of x for each defined adduct.

See also

mass2mz() for the reverse calculation, adductNames() for supported adduct definitions.

Author

Michael Witting, Johannes Rainer

Examples

ion_mass <- c(100, 200, 300)
adduct <- "[M+H]+"

## Calculate m/z of [M+H]+ adduct from neutral mass
mz2mass(ion_mass, adduct)
#>         [M+H]+
#> [1,]  98.99272
#> [2,] 198.99272
#> [3,] 298.99272

ion_mass <- 100
adduct <- "[M+Na]+"

## Calculate m/z of [M+Na]+ adduct from neutral mass
mz2mass(ion_mass, adduct)
#>       [M+Na]+
#> [1,] 77.01078

## Provide a custom adduct definition.
adds <- data.frame(mass_add = c(1, 2, 3), mass_multi = c(1, 2, 0.5))
rownames(adds) <- c("a", "b", "c")
mz2mass(c(100, 200), adds)
#>        a  b   c
#> [1,]  99 49 194
#> [2,] 199 99 394