Establishment of a QuEChERS approach coupled with GC–MS for simultaneous determination of 10 liquid crystal monomers in Chinese herbal medicines from four medicinal parts

Liquid crystal monomers (LCMs) are emerging environmental contaminants with bioaccumulation potential and health risks. Chinese herbal medicines, susceptible to LCM uptake during cultivation or processing, represent a potential human exposure route. However, reliable methods for analyzing LCMs in these complex matrices are lacking. Herein, a modified QuEChERS method coupled with gas chromatography–tandem mass spectrometry (GC–MS) was developed for the determination of 10 LCMs in herbal medicines. Samples were extracted with dichloromethane and cleaned up using mixed sorbents (N-propyl ethylenediamine and octadecylsilane). The method showed excellent linearity (2.0–200.0 μg/L, r 2  > 0.999), with limits of detection and quantification of 0.5–2.0 μg/kg and 1.0–5.0 μg/kg, respectively. Mean recoveries across three spike levels in different matrices ranged from 75.0% to 112.9%, with relative standard deviations of 2.0–8.5% ( n  = 6). In the analysis of 26 real herbal medicines samples, LCMs were detected in mulberry leaf and Salvia miltiorrhiza , indicating a detection frequency of 7.7% and potential contamination in herbal medicines. This reliable and practical method is suitable for routine monitoring of LCM residues in various herbal products.