spectra collected at various retention times. Q4/If this sample is analyzed by L
ID: 523404 • Letter: S
Question
spectra collected at various retention times.Q4/If this sample is analyzed by LC-ESI-MS, how do expect the analytical results to be different from those of GCEI-MS? Be specific in describing the differences observed in the chromatograms and mass spectra. ESI and EI stands for “Electrospray Ionization” and “Electron Impact Ionization”, respectively
Q4/If this sample is analyzed by LC-ESI-MS, how do expect the analytical results to be different from those of GCEI-MS? Be specific in describing the differences observed in the chromatograms and mass spectra. ESI and EI stands for “Electrospray Ionization” and “Electron Impact Ionization”, respectively
Figure la Pyrolysis at 590 C Pyolysis at 358 C Figure 1C Figure id Figure le Figure 1. (a) GC-MS analysis ofa drugsample by pyrolysis at 358 "Cand 590 C(b) Mass spectrum at Scan 1298 or 17.23 min for pyrolysis temperature of at358 "C (c) Identified molecular structure for Scan 1298 or 17.23 min: (d &e;) Mass spectra at39.92 min and 40.75 min for pyrolysis temperature of at 590 "Care identified as methanones, the main psychoactive constituents in the drugofabuse.
Explanation / Answer
The analytical results will be quite different. ECI (Electron Impact Ionization) is a hard ionization technique and requires higher energy. ESI (Electrospray Ionization) is a soft ionization technique and requires less energy. In ECI, a high energy beam of electrons impact upon the analyte leading to extensive fragmentation. Therefore, a vast number of fragments are produced leading to a number of peaks in the spectrum.
On the contrary, ESI is a soft ionization technique. The molecular ion is produced by solvent evaporation and re-evaporation leading to a fine aerosol and consequent ionization. ESI produces a limited number of peaks and hence fewer peaks are seen in the spectrum.
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