Modifier and Additive Effects in the Supercritical Fluid Extraction of Pseudoephedrine Hydrochloride from Spiked-sand and Suphedrine Tablets

In this chapter, the feasibility of extracting a cationic species with carbon dioxide was examined as well as determining what factors may improve its extractability and why. Pseudoephedrine hydrochloride (Figure 5.1) was chosen as our test analyte. Pseudoephedrine hydrochloride is an active ingredient in many pharmaceutical cold formulations and serves as a nasal decongestant. Hedrick et al. investigated the feasibility of extracting nitrogenous bases including triprolidine, sulfamethazine, caffeine, 2,5-lutidine, and pseudoephedrine from aqueous solutions using direct SFE. 1 As expected, the greater the lipophilic characteristics of the basic molecule, the more readily it was extracted with the non-polar fluid carbon dioxide from the polar matrix (i.e. water), therefore, the extraction of the larger organic bases, triprolidine and pseudoephedrine from water was successful. The hydrochloride salts of triprolidine and pseudoephedrine were said to be extracted from the water, however, tetramethylammonium hydroxide (TMAOH) was added to the solution to neutralize the salts thus forming the free bases. No quantitation was reported, and the so-called extracted hydrochlorides were not absolutely identified. Another amine hydrochloride, 3-chloro-p-toluidine hydrochloride (PTH), was successfully extracted from spiked avian feed with 10% methanol-modified carbon dioxide. 2 A two-level, two-factor (2) factorial design was used to examine the effect of