Quantification of Two Sulfide Compounds in Oleo–Gum-Resin Supplement of Ferula foetida Using qH NMR and GC–MS Methods

Asafoetida is an oleo–gum-resin mainly obtained from Ferula foetida in eastern Iran, which is employed for the treatment of stomachaches, acid reflux, nervous system disorders and respiratory diseases. Asafoetida has attracted the attention of researchers due to its sulfide compounds and their proven effects on respiratory illnesses. In this study, the shelf stability of supplement of F. foetida's oleo–gum-resin by quantifying two key sulfide compounds including E/Z-sec-butyl propenyl disulfane and E/Z-(methylthio)propyl 1-propenyl disulfane was evaluated by ¹H NMR (qH NMR) and gas chromatography–mass spectrometry (GC–MS). The similar results were obtained in both qH NMR and GC–MS methods. The qH NMR method showed good linearity in the ranges of 2–12 mg/mL for E/Z-sec-butyl propenyl disulfane and 2.2–17 mg/mL for E/Z-(methylthio) propyl 1-propenyl disulfane with a correlation coefficient of 0.99 and acceptable stability (RSD% ≤ 2.72%) for the quantification of the compounds. Therefore, despite the volatility of disulfide compounds and according to the results, the qH NMR method could be considered adequate method for quantifying these compounds in supplements containing the volatile components that requires extra extraction steps before analyses by other method.