In addition, highly reliable identification was performed by the
measurement of high mass accuracy and isotope pattern using a
single quadrupole mass spectrometer with unit mass resolution.
Typically, this unit mass resolution is able to resolve major isotope
ions at a resolution of 0.5–0.7 Da. (Full Width at Half Maximum,
FWHM) [18]. Here, the instrument line-shape calibration with the
calibrant of PFDTD is created during the analysis of samples as
previously described in the experimental section. Based on the
theoretically calculated mass spectra of PFDTD, the distorted raw
spectrum of a target analyte can be transformed into the symmetrical
and mathematically well-defined calibrated mass spectrum
[15].