APPLICATION OF LOW-RESOLUTION ENERGY-DISPERSIVE X-RAY-FLUORESCENCE SPECTROSCOPY TO TOTAL GLUCOSINOLATE DETERMINATION IN RAPESEED

Due to the high standard of reproducibility and repeatability which is already provided by wavelength X-RF spectrometers it is difficult to see low resolution energy dispersive X-RF instruments entering the fie ld of analyses for official certifications or research purposes. This type of X-RF machines, however, seems to be suitable for the separatio n of yield batches according to their glucosinolate content. The stand ard error of estimation for that application is calculated to 3.5 mumo l/g which is two times higher than those obtained from wavelength disp ersive instruments (1.3 mumol/g) but, however, still much lower than t hose derived from routine NIR instruments with fixed filters (8.9 - 18 .9 mumol/g). Thus this instrument might be an interesting alternative to NIR machines, which are in the same cost range. Although the statis tical values of the results obtained from energy dispersive X-RF are m uch better than those derived from NIR it should be kept in mind, that NIR provides more analytical possibilities for an agrochemical labora tory (e.g. protein and oil determination). For the separation of seed batches it is not necessary to cover the range of high glucosinolate c oncentrations so that the settings of the instrument can be optimized to the lower range of concentrations. This, however, requires that the user need to be supplied with an adapted set of rape-seed reference m aterials for the calibration in a certain range.