Hello.
I have water and sediment samples collected in freshwater, brackish water and marine water environments. I want to keep these samples for a long time and use them in the future for taxonomic analysis of diatoms. These are not cleared samples. So If I replace most of the water by alcohol, how long can I keep these samples?
Dear Anton
In our department there are samples in alcohol diatoms that are 10 years old. All diatoms are visible, although the shade of their cell membrane changes, but morphologically they are identical to fresh samples. When fixing, it is better to pass it through a concentration of 40, 70, 90% etanol.
Regards, Sergey
Ali, as I know it is necessary to replace Lugol's solution once a month?
Dear Anton,
I agree with Sergey Viktorovich, it should be preserved in at least 70% alcohol and kept in a cool place, and it should be stored at -20 degrees if you want to identify it at the genetic level. In such situations, it's best to keep a check on the samples in case the alcohol evaporates. Formalin 4 %, on the other hand, is beneficial for long-term preservation, but it comes with a health warning, as you are aware.
Best regards,
Dear Anton;
Please look at "European Committee for Standardization (2014) Water quality-Guidance for the routine sampling and preparation of benthic diatoms from rivers and lakes. European Standard EN 13946, pp. 17. Brussels"
Best regards
10% formalin is a decent fixative, and we use it in my lab to preserve samples from the McMurdo dry valleys. That being said, I digest samples in hot peroxide to destroy organic material, so the preservation of internal structures does not matter to me, as long as the valves stay intact. As far as I know, ethanol should not damage valves, so your samples should be fine for the foreseeable future.
I used to use Lugol’s solution to keep my algae for future analysis.
Anton Lyakh when it comes to Diatom material I can share the links which has been done work in the similar sector
https://www.researchgate.net/post/Which_is_good_presevative_for_long_time_for_diatom_after_total_cleanig_and_separation_of_them
Protocols for collection and preservation are:
http://wgbis.ces.iisc.ernet.in/energy/water/paper/diatoms_from_aquatic_habitats/preservation.htm
Diatom samples can be preserved in alcohol (usually ethanol or isopropanol) for long-term storage. When stored properly, diatoms can remain well-preserved and suitable for analysis for several years. The exact duration depends on various factors, including the type and concentration of alcohol used, the condition of the diatom samples at the time of preservation, and the storage temperature.
Here are some guidelines for storing diatom samples in alcohol:
The storage duration of diatom samples in alcohol can vary based on the research objectives and specific requirements. Some studies have successfully analyzed diatom samples that were stored in alcohol for several decades, while others may prefer to analyze samples within a few years of collection to minimize any potential degradation.
If you are planning to store diatom samples for an extended period, it is recommended to conduct a pilot study or test the preservation method on a subset of the samples before proceeding with the entire collection. This can help ensure that the storage method maintains the quality and integrity of the diatom samples over the desired duration.
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