I have never had to prepare samples stored in ethanol but if you are worried about it, you could bring sub-samples to a boil for a few minutes. Because ethanol has such a low boiling point, most of it will leave the solution leaving mostly water.

Diatoms sink, and a little raw material will go a long way. I find that if you have really gunky material, a single milliliter is often enough to make several slides. If you can get a small amount of material from the bottom of your containers (let them settle 24 hrs first) you could leave a small amount in the containers you plan to digest the samples in and leave them overnight. The majority of the ethanol as well as some, if not all, of the water will evaporate allowing you to proceed to the peroxide digestion.

Lane Allen Thank you so much for your response. This is helpful. For my first subsample, I rinsed and centrifuged with Millipore water a number of times, but this added a lot of time to my preparation. I will use your methods on my next samples. How do you usually store field samples and prevent growth prior to preparation, if not ethanol?

Also, I see that you work at the diatom lab at University of CO boulder. I have been curious about reaching out to Dr. Spaulding to learn more about a graduate program there. I am interested If you may be willing to connect and tell me more about what you do?

Sincerely,

Anna

I am currently employing the method for my studies, but I have not observed such violent reaction during the hot peroxidase method. Though, one thing to worry about is exposure. So it is better to work in a fume hood.