Agent Lemon, DXM extraction process

[e_jipt]

I have used the Agent Lemon method a few times to extract Dextromethorphan from OTC syrups. I was wondering how it worked chemically. I know that the ammonia pulls the DXM from the syrup, and then the naptha pulls it from the ammonia. Then after that separates (due to naptha being petroleum based right?) Then the lemon juice takes it from the naptha. And that again separates. I know this whole process has to do with polar and non-polar solutions but not exactly sure. I've taken highschool chemistry but that is the extent of my knowledge.

[Rhodium]

You have performed an acid/base extraction. Ammonia is a base, and lemon juice is acidic due to its citric acid content. The theory can be read here:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/rextal.a-b.basics.html

[e_jipt]

I know the DXM can metabolize into DXO over a period of time. Is there anyway to stablize it halfway though the extraction or just evaporate all the material at the end to keep a powdered form. I would prefer to keep the DXM in a citric form as opposed to freebase but if it is ok to leave it in the naptha for a period of time before finishing the extraction I would like to know.