Analytical characterization and differentiation between threo- and erythro-4-fluoroethylphenidate.

Purpose: Methylphenidate analogs appeared on the drug market during the last years. Its analogs contain two chiral centers and, thus, have potential varying configurations (i.e.

[Improvement Method of Confirmation Test of the In-pharmacy Formulation as Topical Medicine No. 37-①].

Topical Medicine No. 37-① is one of the in-pharmacy formulation that specifies a confirmation test (referred hereafter as the conventional method) to identify its ingredient diphenhydramine (DH) by colorimetric test. However, the conventional method is environmentally unfriendly due to the large amount of sample and organic solvent used, and the extraction process is complicated.