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Analytical possibilities in the propolis quality control

Due to its scientifically confirmed biological activity, propolis became a component of numerous medical products. The Croatian legislative regulation still have not given guidelines for the propolis standardisation, but only the recommendations for the synchronization according to the guide that point out to the dry residue. In the EU declaration one can often observe propolis as a component, with its quality been additionally marked with the minimal content of flavonoid galangine. Our Firm concluded that spectrophotometric method with aluminium chloride is quite appropriate for the fast quantification of the flavonoids with the similar structure such as galangine and quercetin. Measurement has been done with the ethanol propolis extract solutions. High-pressure liquid chromatography (HPLC) is much more accurate method for the evaluation of the galangine quantity in the raw material or in the final product. HPLC system with the diode array detector (DAD) can perform accurate determination of several flavonoids simultaneously (galangine, pinocembrine, quercetin etc.). With use of this method one can faster processed the larger number of samples, and there is also a possibility of additional confirmation via characteristic up front recorded UV spectrums of individual flavonoids. In our measurements we have been comparing the dry residue of the various ethanol propolis extract solutions in relation with the galangine and quercetin quantities determined by the use of the spectrophotometric and HPLC analytical methods. The quantity of the dry residue was not in correlation with the values of galangine and quercetin determined by the use of the spectrophotometric and HPLC analytical methods. The values of galangine and quercetin obtained by the use of spectrophotometric analytical method were higher than those obtained by the use of HPLC analytical method which corresponds to a formation of complexes with aluminium chloride with the structurally similar flavones and flavonols. According to our studies, HPLC with DAD is better, more specific and more accurate technique for quantification of individual flavonoids and for the performing of the propolis standardisation towards one of the flavonoids as well.

Propolis; Analysis; Quality Control; HPLC

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