From our experience they are quite stable at 4oC if you use tightly closed vials. However, some commercial standard solutions are labeled "room temp. storage" while others have a "-20 temp" label. You can check the Sigma catalog for example. So, if you are to store for long times, you can freeze them at -20 , but for frequent use refrigeration may be more practical. You can periodically check their stability by GC-MS..

Dear Sir. Concerning your issue about the stability of Geosmin and 2-MIB stock solutions . Stability has been previously reported. For general batch processing, a maximum of 50 samples can be run during a total run time of ± 34 hr. (50 × 41 min per sample). Typical batch sizes of less than 50 samples can therefore be run in just over 24 hr. It was noted that that area counts for geosmin, especially at low concentration, tend to decrease on standing of the sample at room temperature. Maintaining the water samples chilled whilst stored in the autosampler rack until the time of sample analysis, has shown stability of geosmin. This is an important factor to consider when analyzing drinking water samples for presence of geosmin. I think the following below link may help you in your analysis:

https://www.omicsonline.org/method-validation-for-the-trace-analysis-of-geosmin-and-2-methylisoborneol-in-water-by-salt-free-purge-and-trap-sampling-gc-ms-using-the-eclipse-4660-sample-concentrator-2157-7587.1000134.php?aid=7490

Thanks

Thank you so much for your answers!