Application of predicted fragmentation pathways and fragment ion structures for detecting steroids and selective androgen receptor modulators in dietary supplements using liquid chromatography-quadrupole time-of-flight mass spectrometry

Dietary supplements advertised to strengthen muscles have earned fame among athletes. However, several products containing unauthorized compounds are often detected, which can cause a public health risk. Particularly, steroids and selective androgen receptor modulators (SARMs) can cause serious side effects as hormone modulators. In this study, we analyzed 15 steroids and 20 SARMs using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC/QTOFMS) to provide fundamental information about fragmentation pathways and fragment ion structures.

The optimal conditions of LC/QTOFMS were explored to obtain fragmentation patterns for each compound. The optimal conditions were established by comparing the area and height of the precursor ion peak at 125 or 175 V as a fragmentor energy. Furthermore, the optimized spectra were acquired by applying collision energy ranging from 1 to 50 eV. The energy value was selected under the condition that the mass error of precursor ions was less than 10 ppm.

The 35 compounds were classified on the basis of their chemical core structures: arylpropionamide (3 compounds), quinolinone (2), pyrrolidinylbenzonitrile (1), indole (2), tropanol (2), phenylaxadaizole (1), hydantoin (2), phenylthiazole (1), nitrothiophene (1) and steroidal derivative (20). Fragmentation pathways and the chemical structure of each product ion were predicted and identified. Furthermore, the obtained structural information was applied to screen seized samples. As a result, 10 seized samples were confirmed to contain one or more SARMs by comparing each precursor ion and fragmentation pattern.

The application to real samples for accurate screening indicated that the same fragmentation patterns and product ions as one or more SARM standards were detected and identified in the seized samples advertised as muscle building. Therefore, this study can contribute to ensuring the safety of public health through providing fundamental information about the risk of illegal adulteration.