Rapid and sensitive determination of etomidate based on colorimetric assays with a chromium(<scp>iii</scp>) complex

Vaping etomidate is currently a red-hot social issue where the drug abuse problem has led to health concerns and even reported deaths for adolescents. Therefore, a fast, sensitive, and cost-effective detection tool for etomidate is urgently needed to support law enforcement. A chromium(III) complex-based sensor, EtoChrom, is presented in this work as an example of a detection method for etomidate based on a colorimetric assay. This low-priced but novel sensor exhibits an eye-catching colour change from purple to yellow and a bathochromic shift in the absorption band upon etomidate binding. Thus, the result can be seen directly by the naked eye. EtoChrom demonstrated a high precision of up to 2 mg mL^-1 etomidate with a low detection limit of 0.030 mg mL^-1, with the interference from the vape juice and saliva matrices negligible throughout the test. In real etomidate-containing vape juice analysis, EtoChrom can provide accurate results within 1 min, revealing its high potential to serve as an easy-to-handle and cost-effective etomidate detector for rapid on-site screening.