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.