BRAINCAKEModern Analytical Techniques
Revision notes for Modern Analytical Techniques in Edexcel Chemistry (9CH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- High Resolution Mass SpectrometryAn ordinary (low resolution) mass spectrometer gives m/z values to the nearest whole number.
- Precise Molecular MassThe precise molecular mass of a compound is found from the m/z value of its molecular ion, M+ (the whole molecule that has lost one electron), in a…
- ChromatographyChromatography separates and identifies the components of a mixture.
- Thin-Layer ChromatographyIn thin-layer chromatography (TLC), the stationary phase is a thin layer of silica (SiO2) or alumina (Al2O3) spread on a glass, metal or plastic…
- High Performance Liquid ChromatographyHigh performance liquid chromatography (HPLC) separates the components of a liquid mixture quickly and precisely.
- Gas ChromatographyGas chromatography (GC) separates mixtures of volatile compounds.
- Retention TimesIn gas chromatography (GC) and high performance liquid chromatography (HPLC), the components of a mixture are carried through a column by the mobile…
- Nuclear Magnetic ResonanceNuclear magnetic resonance (NMR) spectroscopy is used to work out the structure of organic molecules.
- Chemical ShiftThe position of an NMR signal is given as its chemical shift, δ, measured in parts per million (ppm) relative to a reference compound.
- 13C NMR Spectroscopy13C NMR detects the 13C isotope, which makes up only about 1.1% of carbon atoms.
- 1H NMR Spectroscopy1H NMR (proton NMR) detects hydrogen nuclei.
- Integration TracesThe area under each peak in a 1H NMR spectrum is proportional to the number of hydrogen atoms in that environment.
- Spin-Spin SplittingIn a high resolution 1H NMR spectrum, many peaks are split into a group of closely spaced lines.
- The n+1 RuleThe n+1 rule: a hydrogen environment with n hydrogen atoms on the adjacent carbon atom(s) is split into n + 1 lines. • n = 0: singlet • n = 1…
- Deducing Structures from Combined DataNo single technique identifies an unknown compound on its own.
On the specification
- Topic 19A: Mass Spectrometry
- Topic 19B: Nuclear magnetic resonance (NMR)
- Topic 19C: Chromatography