- What is the purpose of treating your spinach with methanol prior to extraction?
- You are using light petroleum to extract the organic components of your spinach sample. Why does the extraction solvent also contain methanol?
- If you placed some light petroleum and some water in a separating funnel, you would get two layers. Which layer would be on the top and why (Hint: see Manual p 8)?
- By considering their structures (Manual p 2), explain why β-carotene has a higher Rf than xanthophyll.
- Delete the appropriate (bold) words to complete the following:
If the solvent is more polar than the sample, then the sample/solvent binds more strongly to the polar adsorbent of the TLC plate than the sample/solvent, thus the sample ascends the TLC plate quickly/slowly.
- If a compound has an Rf value of 0.5 using 50% dichloromethane/50% light petroleum as eluting solvent, will it then have an Rf value greater or less than 0.5 if the following solvents were used as eluants (Manual p 5):
- a) 80% dichloromethane / 20% light petroleum
- b) 100% light petroleum
- What effect on the Rf value of the compound would be observed if the developing jar had been inadvertently wet (with water) (Manual p 5)? Why?