Spectra analysis

what are the requirements for all spectra?

• requires a pure sample typically free of water

what are the limitations of MS?

• gives no structural information

• destroys sample

what are the limitations of IR?

• cannot determine molecular weight

• cannot locate group positions on a chain

what are the limitations of C-NMR and H-NMR?

• complex structure peaks can overlap

• high costs

what is on the y axis and x axis for all spectra?

MS

x m/z

y relative abundance

IR

x wavenumber cm-1

y transmittance

NMR

x chemical shift

y signal intensity or absorbance

what does each spectra give you?

MS - molecular weight and structure

IR - identification of functional groups - single, double, triple bonds

C-NMR - determines carbon skeleton

H-NMR - splits sample into sub peaks which tell you how many hydrogen atoms are on neighbouring carbons