Instrumental analysis of organic compounds Flashcards
(49 cards)
Base peak
the most intense peak in a mass spectrum, which is assigned a relative abundance of 100%
Fragment ion
simple positively charged fragment formed from the cleavage of bonds in the molecular ion
Fragmentation
the process in which molecular ions undergo bond cleavage to form smaller fragments
Mass/charge ratio (m/z)
the ratio of the mass of an ion relative to its charge
Mass spectrometry
analytical technique used to measure the mass-to-charge ratio of ions in a sample
Molecular ion
the ion formed when a neutral molecule is bombarded with high-energy electrons
Molecular (parent) ion peak
the peak in the mass spectrum that corresponds to the molecular ion, which has the highest m/z ratio
Relative abundance
the abundance/intensity of an ion relative to the base peak
Absorbance
measure of the amount of light that is absorbed by a substance
Fingerprint region
complex absorption pattern in the region between 400 cm−1 and 1500 cm−1 that is unique to each organic compound
Infrared light
invisible electromagnetic radiation that transmits energy
Infrared spectroscopy
qualitative analytical technique that uses infrared radiation to analyse the bond vibrations, providing information about molecular structures and functional groups
Infrared spectrum
graph representing the absorbance of infrared light at different wavelengths within the infrared region of the electromagnetic spectrum
Transmittance
measure of the amount of light that passes through a substance
Wave number
the reciprocal of the wavelength of light measured in cm−1
13C-NMR spectroscopy
analytical technique that uses electromagnetic radiation and magnetic fields to provide information about the number of non-equivalent carbon environments in an organic compound
13C-NMR spectrum
spectrum of chemical shift values in ppm relative to a chemical standard (usually TMS)
Carbon-13 nucleus
the nucleus of the carbon-13 isotope, which has an odd mass, allowing it to be detected by an NMR spectrometer
Chemical shift
the resonant frequency of an atomic nucleus relative to a standard in a magnetic field
Equivalent carbon environments
one or more carbon-13 nuclei attached to the same atom that are in identical chemical environments and are able to combine with adjacent carbon-13 nuclei to show as one peak in a spectrum
Non-equivalent carbon environments
one or more carbon-13 nuclei attached to different atoms that are in different chemical environments
Symmetrical
made up of exactly identical parts facing each other or around an axis
1H-NMR (proton NMR) spectroscopy
analytical technique that uses electromagnetic radiation and magnetic fields to provide information about the number of non-equivalent proton environments in an organic compound and the number of protons in those environments
1H-NMR spectrum
spectrum of chemical shift values in ppm relative to a chemical standard (usually TMS)
