Extract fluorescence peaks
Value
An object of class eemlist.
A data frame containing peaks B, T, A, M and C for each eem. See details for more information.
Details
According to Coble (1996), peaks are defined as follow:
Peak B: ex = 275 nm, em = 310 nm
Peak T: ex = 275 nm, em = 340 nm
Peak A: ex = 260 nm, em = 380:460 nm
Peak M: ex = 312 nm, em = 380:420 nm
peak C: ex = 350 nm, em = 420:480 nm
Given that peaks A, M and C are not defined at fix emission wavelength, the maximum fluorescence value in the region is extracted.
Interpolation
Different excitation and emission wavelengths are often used to measure
EEMs. Hence, it is possible to have mismatchs between measured wavelengths
and wavelengths used to calculate specific metrics. In these
circumstances, EEMs are interpolated using the
interp2 function from the parcma library. A
message warning the user will be prompted if data interpolation is
performed.
References
Coble, P. G. (1996). Characterization of marine and terrestrial DOM in seawater using excitation-emission matrix spectroscopy. Marine Chemistry, 51(4), 325-346.
Examples
file <- system.file("extdata/cary/scans_day_1/", "sample1.csv", package = "eemR")
eem <- eem_read(file, import_function = "cary")
eem_coble_peaks(eem)
#> Warning: This metric uses either excitation or emission wavelengths that were not present in the data. Data has been interpolated to fit the requested wavelengths.
#> sample b t a m c
#> 1 sample1 1.545298 1.060331 3.731836 2.424096 1.814941