Table of Contents

Sugar analysis using alditol trifluoroacetates

Introduction

For a general introduction to hydrolysis of glycosides see Sugar analysis using alditol acetates. This procedure gives another type of alditol derivative, trifluoroacetates, suitable for the separation on chiral columns. The derivative is more labile than acetates and samples that have been standing may require reacylation.

Flow scheme

Hydrolysis Reduction Trifluoroacetylation

Reagents

Full list of chemicals

Procedure

  1. Transfer sample (ca 0.2 mg, ~1 mmol) to a 13 x 100 mm screw cap tube.
  2. Hydrolyse in ~0.3 mL 2M TFA at 120 °C for 2h or in 0.5M TFA at 100 °C 12-16 h.
  3. Evaporate the solution to dryness by a stream of compressed air, add 0.5 mL MeOH, and evaporate. Repeat once.
  4. Reduce with 0.3 mL fresh solution of NaBH4 in NH3 for 30 min at 20 °C.
  5. Quench with 0.5 mL 10% HOAc in MeOH, evaporate to dryness. Add 0.5 mL 10% HOAc in MeOH and evaporate to dryness. Repeat once or twice. Add 0.5 mL MeOH and evaporate to dryness. Repeat once or twice.
  6. Trifluoroacetylate with 50 µL Ac2O and 50 µL acetonitrile 80 °C 4 min. Allow to cool for 10 minutes. Alt. If the peaks on GLC look bad evaporate to dryness and dissolve in dry CH2Cl2.
  7. Inject the whole reaction mixture on GLC

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