In order to effectively and quickly monitor such illegal food and drugs, simultaneous screening and quantitative analysis for multiple compounds are needed. In this study, we established a method of identifying fragmentation ions of 45 compounds for weight loss using liquid chromatography and high‐resolution mass spectrometry and developed a quantitation method through liquid chromatography and tandem mass spectrometry. Note that, 656 samples selected as health functional food, food, and illegal drug were applied. The detection rate of banned weight loss compounds in health functional food, food, and illegal drug was showed as 19.2, 27.3, 40.7%, respectively. Among them, sibutramine, sennoside A and B, ephedrine were most frequently detected in 237 samples that contained weight loss compounds. The detection range about sibutramine was 0.03–159.3 mg/g, sennoside was 0.1–97.6 mg/g, and ephedrine was 0.1–587.7 mg/g in the detected 237 samples. In addition, the unknown compounds not included in our simultaneous analysis method in some samples were identified as furosemide and chlorpheniramine. High selectivity of high resolution mass spectrometry combined with these fragmentation pathways and tandem mass spectrometry methods can be successfully applied to screening and identifying 45 weight loss compounds for continuous blocking and supervision of illegally distributed health functional food, food, and illegal drug.

Rationale With the development of the Internet and social network services, the public access to or use of illegal products has been increased via on/offline black markets. Steroids refer to the compounds yielding strong treatment effects on some diseases or muscle building, and are classified as the pharmaceutical compounds that are prohibited for personal use without a prescription. The prohibition is made for their potential risk to cause serious adverse effects along with their efficacies. Methods To monitor the distribution of illicit products containing steroids, a simple and reliable analytical method was established and validated, allowing rapid and simultaneous determination of 54 steroids in them. During the screening, LC‐Q‐Orbitrap/MS was performed first followed by quantitative analysis using LC–MS/MS. For the accurate and reliable analysis, the samples were extracted using QuEChERS to reduce the matrix effect. Results After the screening of 617 illegal samples advertised as being effective in alleviating various diseases or improving athletic performance with the established LC‐Q‐Orbitrap/MS method, the validated LC–MS/MS method was used to perform the quantitative analysis of the detected steroids. Of these, 142 samples were adulterated with steroids, and several samples with two or more steroids were detected. Due to the lack of previous studies on the toxicity of these illicit products, the side effects of consuming them are unpredictable and could be harmful. Conclusions The development of LC‐Q‐Orbitrap/MS method accompanied by LC–MS/MS could be successfully applied to the inspection of illegal steroid products for public health, enabling the rapid and accurate detection of analytes and incorporation of non‐analyte components.

Natural-derived steroids and their analogues are present in various plants and insects. To minimize the chance of missing a positive doping test and avoiding potentially serious health problems, adequate screening methods are necessary for the detection of a wide range of natural-derived steroids and their analogues in dietary supplements. In this study, an accurate and simple liquid-chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine and quantify the natural-derived steroids and their analogues according to the International Conference on Harmonization of technical