Emulation and backtracking of HPLC chromatographic profiles for glucosinolate valuation from total sulphur concentrations in oilseed rape seeds*

The relationship between the total glucosinolate (GSL) concentration calculated from the total sulfur concentration which had been measured by means of X-ray fluorescence spectroscopy and the content of glucobrassicanapine, glucobrassicine, gluconapine, napoleiferine, progoitrine and 4-hydroxiglucobrassicine in the seeds which were measured by chromatographic methods was determined in the line of quality assessment studies of oilseed rape standard reference materials. The constant ratio between individual aliphatic GSLs which is independent of the total GSL content allows to emulating the concentration of individual GSLs from the total GSL content on basis of the total S content. As indol GSLs represent a constant background value of the total GSL content their estimated concentration is added to the calculated sum of aliphatic GSLs in order to obtain an emulated total GSL content. In a simple program written in BASIC the typical background variability of individual GSLs can be randomly added to the results which yields different chromatograms that are statistically not different from true HPLC chromatograms. This may assist in distinguishing true experimental effects in studies targeting effects on individual GSLs from those of background analytical error variability. The program may also be used for an independent verification of HPLC chromatograms of GSLs in oilseed rape as it allows backtracking of a given total GSL content to its expected individual GSL concentrations in chromatographic analysis. in memoriam Prof. Dr. RichardMarquardt, Giessen (19.05.1938 - 16.12.2010)