Analytical techniques (A Level)

You will be able to

• Calculate an Rf value and explain differences in Rf in terms of interaction with the stationary phase and solubility in the mobile phase.
• Explain how changing the polarity of the mobile phase changes the Rf values on a TLC plate.
• Interpret a gas chromatogram: compare retention times with a reference and calculate the percentage composition from the peak areas.

You will be able to

• Deduce the number and type of proton environments from the chemical shifts, the relative peak areas and the n + 1 splitting pattern.
• Predict the number of peaks in the ¹³C NMR spectrum of a molecule and the chemical shift range of each carbon environment.
• Use IR bands, the molecular ion and proton exchange with D₂O to decide between possible structures.