Isopropyl alcohol: A replacement for tertiary-butyl alcohol in pollen preparations

We propose an alternative dehydrating agent for the preparation of pollen samples mounted in silicone oil. Isopropyl alcohol (propan-2-ol, or ‘IPA’) proves to be miscible with both water and silicone oil, and unlike tertiary-butyl alcohol (2-methyl-2-propanol, or ‘TBA’), the conventional dehydrating agent, IPA does not freeze at room temperature. Pollen preparations using IPA are therefore less problematic, especially in cold weather. Photos of fossil pollen samples prepared three months previous using IPA as a dehydrating agent show no difference to those prepared at the same time using TBA. We observed no size difference between Corylus avellana pollen grains dehydrated with IPA compared to those dehydrated using TBA in identically prepared samples. We also find that IPA evaporates from the pollen residue and silicone oil mixture more readily than TBA.