High efficiency screening of nine lipid-lowering adulterants in herbal dietary supplements using thin layer chromatography coupled with surface enhanced Raman spectroscopy

Adulteration of herbal dietary supplements (HDSs) with undeclared synthetic drugs is a world-wide problem that poses a serious threat to human health. Methods ensuring the quality and safety of these supplements need to be developed. Herein, for the first time, highly sensitive thin layer chromatography combined with surface enhanced Raman spectroscopy (TLC-SERS) for the high efficiency screening of HDSs adulterated with up to nine lipid-lowering agents (LLAs) was put forward. After the optimization of two types of thin layer plates and several mobile phases, the nine different LLAs were well separated from the complex HDS matrix. Then, with the relatively universal SERS active silver colloids, all nine analytes presented abundant specific features for identification. This method was highly sensitive which enabled successful detection when the adulteration amount was as low as 0.002% (w/w). Moreover, practical applications of the established coupled method were demonstrated with the rapid analysis of twelve real HDS samples, one of which was found to be adulterated with simvastatin (SIM). The identification results were then verified by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) analysis. The proposed method is simple and rapid, and has good prospects for high efficiency screening and sensitive analysis of multiple adulterants in HDSs.