Instrumental analysis of organic compounds Flashcards
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)
Equivalent proton environments
one or more protons (hydrogen nuclei) attached to the same atom that are in identical environments and are able to combine with adjacent protons to show as one set of peaks in a spectrum
High resolution
showing both singular peaks and distinct sets of peaks with splitting patterns
Hydrogen nucleus
the nucleus of the hydrogen atom, which has an odd mass, allowing it to be detected by an NMR spectrometer
Integration curve
curve on a 1H-NMR spectrum showing the relative number of protons in a proton environment
Low resolution
showing only singular peaks without splitting patterns
n+1 rule
the number of splits in a peak is equal to the number of protons in the neighbouring proton environment(s) (n)+1
Non-equivalent proton environments
one or more protons (hydrogen nuclei) attached to different atoms that are in different chemical environments, causing splitting to adjacent protons
Splitting pattern
the number of peaks shown in a set of peaks corresponding to a single non-equivalent proton environment`
Adsorption
adhering of a component onto the stationary phase
Calibration curve
a graphical representation of the relationship between the concentration of a substance and its corresponding response on a detector
Chromatogram
visual output of chromatography
Desorption
release of a component from the stationary phase by dissolving
Eluent
solvent fluid that moves through a chromatography system
High performance liquid chromatography (HPLC)
chromatography technique in which the mobile phase and sample are pumped through a tightly packed stationary phase under pressure
Interpolate
infer values from a graph within the range of data
Miscibility
ability of two or more substances to dissolve in each other
Mobile phase
fluid in a chromatography system that carries the sample over the stationary phase
Origin
line at which samples are placed in paper and thin-layer chromatography
Paper chromatography
chromatography technique using absorbent paper
Peak area
the area enclosed between the peak and the baseline on a chromatogram
Retention time (Rt)
time taken for a component in a sample to pass through an HPLC column
Resolution (chromatography)
degree of separation between two different peaks on a chromatogram
Stationary phase
solid onto which the components of a sample adsorb
Thin-layer chromatography
chromatography technique using a thin stationary phase supported by an inert backing
LC-MS
combined use of liquid chromatography and mass spectrometry
