Dear Sir. Concerning your issue about how long can digested plant samples be stored before testing for heavy metal analysis by AAS. Samples should be stored in a freezer until 2-3 hours before they are scheduled for analysis, at which time they are allowed to thaw at room temperature. Any remaining sample is stored in the freezer. Plastic forceps and plastic spatulas are used to handle the tissue samples. Plastic pipettes are used to withdraw the serum samples. If the whole tissue is not to be taken for analysis, it is transferred from the sample container to a disposable PE dish where it is divided with plastic forceps or spatulas,and the vessel should be capped . The elemental content in question should be determined as soon as possible after the digestion process. Although the digestions solutions probably remain stable for a fairly long period of time (up to two months at least, based on past experience) longer periods of storage may lead to distortions of elemental contents caused by adsorption at the walls of the vessel as well as precipitation. If samples stored for longer periods of time are to be used, their suitability should be verified. I think the following below links may help you in your issue:

http://www.ime.fraunhofer.de/content/dam/ime/en/documents/AE/SOP_Digestion.pdf

https://www.inorganicventures.com/acid-digestions-organic-samples

Thanks

it is best if you refrigerate the sample and if possible test it as soon as u can to avoid contamination and to obtain best results

Agree with Dr. Isam Eldin Hussein Elgailani