Semi-quantitative determination of designer steroids by high-performance liquid chromatography with ultraviolet detection in the absence of reference material.

New designer steroids are continually being encountered in dietary supplements that claim to increase muscle mass, but quantitative analysis of such ingredients is challenging due to the availability, quality, or cost of commercial reference materials. Although standard reference material typically becomes available for these emerging compounds, laboratories often face the challenge of finding properly certified materials from accredited suppliers, due to traceability requirements. Several of these designer steroids have been isolated and identified using multiple structural elucidation tools. Structural characteristics of these compounds of interest were evaluated and molar absorptivity data was collected and compared to several readily available steroid standards using ultraviolet/visible spectroscopy. This approach was used to find suitable compounds for use as surrogate reference materials in the semi-quantitative determination of two designer steroids, 1-dehydroepiandrosterone (1-androsterone) and 6ß-chloro-4-androsten-17ß-ol-3-one (6ß-chlorotestosterone). Laboratory-fortified matrix samples and dietary supplement samples were analyzed using this method for the estimation of 1-androsterone and 6ß-chlorotestosterone by HPLC-UV. Assay values obtained for the estimation of 1-androsterone in a dietary supplement sample using a prasterone or dehydroepiandrosterone (DHEA) standard curve were 100% of those obtained using a 1-androsterone reference standard, once it became commercially available. Estimations for 6ß-chlorotestosterone in laboratory-fortified matrix samples using a testosterone standard curve were 92%-93% of those obtained using isolated 6ß-chlorotestosterone as "reference material."

Isolation and structural characterization of a new tadalafil analog (chloropropanoylpretadalafil) found in a dietary supplement.

A screen for known PDE-5 inhibitors in a dietary supplement product marketed for "enhanced sexual performance" detected a compound that structurally resembled chloropretadalafil, a known analog of tadalafil. The compound was isolated from the supplement matrix using high performance liquid chromatography with ultraviolet detection (HPLC-UV) and a fraction collector, and was further characterized using gas chromatography with Fourier Transform infrared detection and mass spectral detection (GC/FT-IR/MS), as well as high resolution mass spectrometry (HRMS). The analog had an accurate mass of m/z 441.1216 (error is 0.8706ppm) for the protonated species [M+H](+), corresponding to a molecular formula of C23H22ClN2O5. HRAM and GC/FT-IR/MS mass spectral fragmentation data suggested that the modification is a chloropropanoyl moiety extending from the nitrogen on the piperidine ring of chloropretadalafil. The proposed new analog has been named chloropropanoylpretadalafil.

Isolation and structural characterization of a new tadalafil analog (2-hydroxyethylnortadalafil) found in a dietary supplement.

A screen for known PDE-5 inhibitors in a dietary supplement product marketed for "enhanced sexual performance" detected a compound that structurally resembled tadalafil. The compound was isolated from the supplement matrix using high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and a fraction collector, and was further characterized using nuclear magnetic resonance (NMR), liquid chromatography-mass spectrometry (LC-MS), as well as high-resolution accurate mass mass spectrometry (HRAM-MS). The analog had an accurate mass of m/z 420.15614 (error is 1.77235ppm) for the protonated species [M+H](+), corresponding to a molecular formula of C23H22N3O5. Mass spectral fragmentation data suggested that the modification occurred in place of the CH3 located on the pyrazinopyridoindole-1,4-dione of tadalafil. NMR was utilized to further elucidate the configuration of the substitution. The analysis indicated that the moiety is a CH2CH2OH, hydroxyethyl group. The new analog has been named 2-hydroxyethylnortadalafil.

Isolation and structural characterization of two tadalafil analogs found in dietary supplements.

During routine screenings of two "libido enhancer" dietary supplements using LC-MS(n), two compounds were detected that displayed structural similarities to tadalafil. These compounds were isolated from the supplements using high-performance liquid chromatography with fraction collection, and were characterized further using accurate mass determination and NMR. "Compound 1" had an m/z of 434 for the [M+H]⁺ ion, with a corresponding chemical formula of C24H24N3O5. "Compound 2" had an m/z of 432 for the [M+H]⁺ ion, with a corresponding chemical formula of C25H26N3O4. Although mass spectrometry indicated that these modifications occurred in place of the -CH3 found on the pyrazinopyridoindole-1,4-dione of tadalafil, NMR was required to elucidate the correct configurations of these substitutions. The data obtained using NMR indicated that the structure of the -C3H7O moiety found in Compound 1 was 2-hydroxypropyl, and the -C4H9 in Compound 2 was n-butyl. These new analogs were given the names 2-hydroxypropylnortadalafil and n-butylnortadalafil, respectively.