Quantification of glucosinolates in nozawana (Brassica rapa L.) and evaluation via single- and multi-laboratory validation studies

Abstract

Glucosinolates in cruciferous plants have been reported to exhibit various health benefits. Consequently, several studies have focused on the quantification of glucosinolates. A simple method was developed in this study to quantify glucosinolates in nozawana (Brassica rapa L.), and the validity of the developed method was evaluated. Glucosinolates were extracted from a dry powder of nozawana, solid-phase extraction was performed, and liquid chromatography–mass spectrometry measurements were conducted. A single-laboratory validation study on the developed method suggested that the relative repeatability standard deviation, relative intermediate standard deviation, and recovery rate of the spike and recovery tests complied with the accuracy standards of the Association of Official Analytical Chemists (AOAC) guidelines. Additionally, a multi-laboratory (three laboratories) validation study revealed that although the Horwitz ratio (HorRat) for trace glucosinolates was over 2, that for the primary glucosinolates in nozawana was less than 2, indicating an appreciable degree of reproducibility.