Development and Validation of a Spectrophotometric Method for Quantification of Total Glucosinolates in Cruciferous Vegetables
2012
Gallaher, Cynthia M. | Gallaher, Daniel D. | Peterson, Sabrina
Given their putative role in chemoprevention, validated methods are needed for quantification of total glucosinolates. Based on the colorimetric reaction of ferricyanide with 1-thioglucose, released by alkaline hydrolysis of glucosinolates, we developed a simple and sensitive method for spectrophotometric quantification of total glucosinolates in cruciferous vegetables. Lyophilized and ground vegetables are extracted with 80% boiling methanol. Extracted glucosinolates are isolated using a strong anion exchange column and then hydrolyzed with 2 N NaOH to release 1-thioglucose. Ferricyanide is added, and the decrease in absorbance is measured at 420 nm, with final values adjusted for background. Recovery of internal standard (sinigrin) was 107%. Intra- and interassay coefficients of variation were 5.4% and 15.8%, respectively. Dose response was linear with sinigrin and amount of plant material extracted (R² ≥ 0.99). Using sinigrin, the lower limit of quantification was 0.6 mg. This straightforward method may be an alternative to time-consuming and costly chromatographic methods.
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