Quantitative analysis of S-Allylcysteine ??in black garlic via Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

Abstract

Do Chau Minh Vinh Tho, Huynh Phuong Thao, Nguyen Duc Tuan, Andreas Zemann

The biological effects of black garlic are stronger than those of fresh garlic, but despite the increasing manufacture of black garlic products, no specifications for controlling their quality have been identified. The most commonly used biological marker of quality is S-allylcysteine (SAC), which is a core active compound in the aforementioned products. SAC content is typically determined using high-performance liquid chromatography with ultraviolet detection, but this method presents many problems because of its complex matrices. To determine the content of SAC in black garlic, this study established a sensitive and reproducible method grounded in ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry. The instrument used is equipped with a triple quadrupole mass detector with an electrospray ionization source. The analysis involved solid-phase extraction using a strongly acidic cationic exchange agent, which enabled the direct examination of samples without the need for derivatization and the determination of SAC content in 5 min. The established method was fully validated in terms of linearity, sensitivity, precision, repeatability, and recovery and was successfully applied in characterizing the quality of some black garlic products manufactured in Vietnam. The proposed procedure exhibited high linearity (R2 = 0.9993) at a limit of detection of 0.25 ng/mL, which is lower than those of other assay techniques. The results indicated that various black garlic products have different SAC contents. This study may be useful in the development of standards for the quality of black garlic.