Development of Liquid Chromatography-Mass Spectrometry (LC-MS) Method for Quantification of Broccoli Sulforaphane

Abstract

Sulforaphane (SFN) is an isothiocyanate and the product of the hydrolysis of glucoraphanin (GRA) by myrosinase. Broccoli is one of the rich sources of GRA and thus SFN. SFN possess a wide range of bioactivities and is considered an anti-cancer phytochemical. Most of the current common methods used to quantify SFN are based on high-pressure liquid chromatography (HPLC) with diode array detection (DAD) — also known as HPLC-DAD. Although this technique has shown encouraging results, the detection of SFN by DAD is relatively weak and affected by high interference of sample matrices. Therefore, the aim of this study was to develop a liquid chromatography-mass spectrometry (LC-MS) method in which SFN is identified by molecular mass to give more accurate results. The developed method demonstrated a highly reproducible retention time (7.204 ± 0.008 min), producing a sharp, symmetrical and well-defined sulforaphane peak in standard and test samples. The most dominant ion of sulforaphane in the pure and test samples was 178 m/z ([M + H]^+). In terms of linearity, the calibration curve had a coefficient of determination (R^2) of 0.9963. The limit of detection of this method is 1.3 ng/mL, and the limit of quantification is 3.9 ng/mL, indicating high sensitivity. The uniformity of peak shape and retention time in both pure and test samples were the same suggesting excellent selectivity. Overall, the developed method showed promising results in identifying and quantifying broccoli SFN.