Comprehensive analysis of respiratory pharmaceuticals in dietary supplements using advanced chromatographic techniques

Recently, the number of people suffering from respiratory symptoms has continued to increase because of COVID-19 and particulate contamination. Accordingly, the demand for respiratory-related dietary supplements is increasing. Over the past few years, dietary supplements adulterated with pharmaceutical drugs have continued to appear, increasing the risk of side effects; thus, preventive measures are needed. In this study, we developed a simultaneous analysis method for 11 respiratory-related pharmaceutical compounds using ultra-performance liquid chromatography with a photodiode array (UPLC-PDA). The sample preparation method was optimized by comparing filtration and two clean-up methods (QuEChERS), for solid and liquid formulations, and the optimal analytical conditions were established by comparing various analysis parameters. Concerning method validation, all parameters meet International Council for Harmonisation guidelines. Subsequently, 54 types of dietary supplements promoting relief of respiratory-related symptoms were purchased online and analyzed using UPLC-PDA. As a result, theobromine, azelastine, and dexamethasone were detected in three products. In addition, the detected compounds were confirmed by comparing fragmentation patterns using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). This study will contribute to preemptively blocking dietary supplements adulterated with respiratory-related drugs from entering the market and can be used as a reference for future research.