HPTLC Screening of Weight Loss Products for Deliberately Added Undeclared Synthetic Drugs.

Background: The proposed HPTLC method combines features of the existing methods for (1) the detection of sibutramine and (2) for the detection of phosphodiesterase type 5 inhibitors and analogs. Objective: The method permits effective screening for the presence of nine adulterants in finished products, including tablets, capsules, and "instant coffee" powders. Methods: All products were prepared for analysis using the same simple procedure: ultrasound-assisted extraction in methanol for 30 min followed by centrifugation or filtration. Results: The retardation factor (RF) values of individual zones afford preliminary identification of potential adulterants. Scanning densitometry enables comparison of recorded UV spectra with those of known standard compounds and provides further structural information. Conclusions: The method was successfully applied to 12 commercial products. Of those, nine products tested positive for at least one undeclared component.

Simultaneous Detection of Three Phosphodiesterase Type 5 Inhibitors and Eight of Their Analogs in Lifestyle Products and Screening for Adulterants by High-Performance Thin-Layer Chromatography.

An HPTLC method is proposed to permit effective screening for the presence of three phosphodiesterase type 5 inhibitors (PDE5-Is; sildenafil, vardenafil, and tadalafil) and eight of their analogs (hydroxyacetildenafil, homosildenafil, thiohomosildenafil, acetildenafil, acetaminotadalafil, propoxyphenyl hydroxyhomosildenafil, hydroxyhomosildenafil, and hydroxythiohomosildenafil) in finished products, including tablets, capsules, chocolate, instant coffee, syrup, and chewing gum. For all the finished products, the same simple sample preparation may be applied: ultrasound-assisted extraction in 10 mL methanol for 30 min followed by centrifugation. The Rf values of individual HPTLC bands afford preliminary identification of potential PDE5-Is. Scanning densitometry capabilities enable comparison of the unknown UV spectra with those of known standard compounds and allow further structural insight. Mass spectrometric analysis of the material derived from individual zones supplies an additional degree of confidence. Significantly, the proposed screening technique allows focus on the already known PDE5 Is and provides a platform for isolation and chemical categorization of the newly-synthesized analogs. Furthermore, the scope could be expanded to other therapeutic categories (e.g., analgesics, antidiabetics, and anorexiants) that are occasionally coadulterated along with the PDE5-Is. The method was successfully applied to screening of 45 commercial lifestyle products. Of those, 31 products tested positive for at least one illegal component (sildenafil, tadalafil, propoxyphenyl hydroxyhomosildenafil, or dimethylsildenafil).