Bestimmung des Gesamtglucosinolatgehaltes in vegetativen Pflanzenteilen durch quantitative Analyse enzymatisch freisetzbaren Sulfates

Summary

With regard to agronomical and ecological aspects there is an increasing interest in total glucosinolate determination in vegetative plant materials. In contrast to time and work consuming chromatographic and insufficient colorimetric methods commonly used, a new simple as well as rapid method is presented, which bases on the enzymatical release of sulfate from the glucosinolate molecule. In order to avoid losses of glucosinolates during sampling and preparation for the analysis of vegetative samples total and undamaged plants are dried at 85 °C. The extraction of free sulfate is done by an 1∶20 extract in 1 mol/l ascorbic acid, whereas the enzymatically released sulfate is determined by an 1∶20 extract in an aqueous solution containing 750 units/ml H1-sulfatase. In the next step sulfate is precipitated from a defined Ba-solution and quantified indirectly by an emission-spectrometric determination of the remaining Ba-concentration. The glucosinolate content of the sample results from differences in the sulfate concentrations of both extracts. On an average 98.4% of pure sinigrin added to a model system was recovered in the experiments. A comparison of results determined by the enzymatic method with HPLC yields a close (r = 0.98) correlation between both methods.