Fast and simple solid phase extraction-based method for glucosinolate determination: an alternative to ISO-9167 method

Authors: LI, YANFANG - University Of Maryland; ZHANG, MENGLIANG - Middle Tennessee State University; Pehrsson, Pamela; Harnly, James - Jim; Chen, Pei; Sun, Jianghao

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2024
Publication Date: 2/21/2024
Citation: Li, Y., Zhang, M., Pehrsson, P.R., Harnly, J.M., Chen, P., Sun, J. 2024. Fast and simple solid phase extraction-based method for glucosinolate determination: an alternative to ISO-9167 method. Foods. 13(5):650. https://doi.org/10.3390/foods13050650.
DOI: https://doi.org/10.3390/foods13050650

Interpretive Summary: Glucosinolates (GLSs) are a group of important secondary metabolites with various health beneficial effects, which are abundant in the Brassica family. Accurate quantification of GLSs in plant materials is crucial for nutritional labeling, dietary assessment, and plant breeding programs. Inaccurate quantification of GLSs can lead to misleading results in human nutritional studies and mislabeling of commercial products. However, quantifying total or individual GLSs has faced challenges due to lack of pure GLS reference compounds. The widely adopted ISO 9167 method for quantification of total and individual GLSs has several challenges. First, there is no commercial Sepharose CL-6B (or Sephadex A25) anion exchange columns ready for use. Preparation of columns with DEAE Sepharose CL-6B (or Sephadex A25) resin is time-consuming, exhibits low repeatability, is less user-friendly for new operators, and proves challenging to scale up for a large number of samples. Furthermore, interference compounds exhibit absorbance at 229 nm which will cause incorrect quantification of GLSs. A more efficient and precise extraction and quantification method that improves upon the dated ISO method is clearly needed. To address this issues,the present study developed a fast and simple method based on weak anion exchange solid-phase extraction (SPE) for determination of GLSs as an alternative to the ISO method. The applicability of the SPE method has been tested with ten brassica vagetables. The developed SPE method is simpler and more efficient, allowing application to a large sample size with reduced analysis time, improved repeatability and accuracy, and possible automation.

Technical Abstract: Glucosinolates (GLSs) are a well-studied sulfur-containing compound found in Brassicaceae plants that play critical roles in plant resistance and human health. Correctly identifying and reliably quantifying total and individual GLS content is of great importance. An improved method as an alternative to the ISO 9167-1 (ISO) method was developed in the present study. An efficient extraction and purification procedure was proposed with a commercially available dimethylaminopropyl (DEA)-based weak anion exchange solid-phase extraction (SPE) cartridge instead of using the self-prepared ion-exchange columns in the ISO method. The GLSs were identified by ultra high-performance liquid chromatography (UHPLC) high-resolution mass spectrometry (HRMS). The method demonstrated comparable quantification of total and individual GLSs on certified rapeseeds and other Brassica vegetables compared to the ISO method. The developed SPE method is simpler and more efficient, allowing application to a large sample size with reduced analysis time, improved repeatability and accuracy, and possible automation.