[Rapid Screening of Etomidate and Its Analogues Using a Portable Mass Spectrometer]

To establish a rapid screening and analysis method for etomidate and its analogues using a portable mass spectrometer equipped with a thermal desorption-atmospheric pressure chemical ionization source-linear ion trap.

A 10 μL aliquot of a standard solution at a concentration of 1 μg/mL was taken, and after the solvent evaporated, the sample was inserted into the inlet of the portable mass spectrometer for detection. By adjusting the collision-induced dissociation parameters, the molecular ion peak and fragment ion peak information of the standard were obtained and used to establish a reference database. In addition, the method was applied to 29 seized liquid and plant samples.

A screening system for etomidate and its analogues was established based on the portable mass spectrometer and the corresponding mass spectrometry library. The system enables qualitative screening analysis by identifying primary protonated molecular ions and secondary product ions of etomidate and its analogues. The limits of detection for etomidate and its 12 analogues ranged from 0.1 to 10 μg/mL. Etomidate and its analogues were detected in all 29 liquid and plant samples. However, this method could not distinguish between isomeric imidazole esters, such as isopropoxate and propoxate. Additionally, when testing 2-SH-etomidate, there was a false positive for the detection of etomidate.

This study established a rapid screening method for etomidate and its analogues using a portable mass spectrometer. The method combines the high sensitivity of mass spectrome-try with the on-site applicability of portable devices, significantly improving detection efficiency and meeting the on-site detection needs of etomidate and its analogues.