I’ve been asked a number of times, and again just last week, the following:
Is it OK to do my hitbodedut in Shemonah Esrei (aka the Amidah)?
No. Interestingly—and somewhat counter-intuitive—even though the Amidah was meant to be a replacement for one’s private prayer (see Rambam, Hilkhot Tefilah Chapter 1), Shemonah Esrei is to be used only for praising God and making requests from Him.
This is true not only in the berakhah of Shomeia Tefilah, but also in the Eloky Netzor. Even though these two parts of the Amidah are open-ended and a “blank” one may fill in for any prayer one chooses to add, they must nonetheless be used only for making requests. Even when one wants to accept upon himself an optional fast (in Eloky Netzor), he does so by couching it in a request.
So, you will have to save your deveikut for another time. However, if you need to split your hitbodedut time into two or more periods, you may use either of these sections of Shemonah Esrei for the “request part.”