The content of HMF in honey and food of plant origin is the subject of many scientific kinds of research, primary for two reasons, firstly its toxicity, secondly, its appearance in honey and food as indicators of the age of food, its way of storing or processing. In this paper, the results of the intralaboratory validation of HPLC method for determining the content of HMF in honey as well as the results of testing fresh samples of honey produced in BiH in 2018 are given. This method is very similar to the ICH [1] method for honey, while innovation in this study is a ballast materials sedimentation by the Carez I and Carez II reagents. The paper gives the results of method validation of the following parameters: interference, specificity, linearity, LOD (limit of detection), LOQ (limit of quantification), precision, accuracy and measuring range. The measuring range of the method is from 60μg/kg to ≥ 100mg/kg with a coefficient of linearity r2 = 0,99999. LOQ of 60μg/kg had a slightly higher value of deviation, but it has no relevance to the maximum residue level (MRL) value of 40mg/kg which is significantly higher. As proof of performance, validation is also accomplished a satisfactory result of the proficiency test. After validation was performed, 21 samples of fresh honey of different biological and geographical origins produced in B&H were tested: 8 acacia, 4 honeydews, 3 chestnuts, 4 meadows, 1 floral and 1 heather. The obtained results ranged from 0.02mg/kg (honey Acacia) to 27.40mg/kg (medow).
Four new heteroleptic copper(II) complexes having chalcone or flavonol ligands and Schiff base (N-phenyl-5-chlorosalicylideneimine) as co-ligand were prepared, chemically and structurally characterized and investigated as functional biomimetic catecholase models. The complexes were prepared by the solution synthesis and crystal and molecular structures were determined by X-ray diffraction. Complexes were chemically characterized by elemental analysis, infrared and electronic absorption spectroscopy as well as by electrochemical measurements. Copper(II) chalcone complexes, with square-pyramidal CuO4N core, are binuclear, featuring phenolate oxygen from the Schiff base as a bridging atom, while copper(II) flavonol complexes are mononuclear, and reveal a square planar CuO3N coordination core. Catalytic activity of the complexes in 3,5-di-tert-butylcatechol oxidation was confirmed by spectrophotometric and electrochemical measurements. Kinetic measurements revealed that the binuclear (chalcone-containing) complexes have enhanced catalytic activity as compared to the mononuclear Cu(II) flavonol complexes. Relatively high kcat values (300-750 h-1) confirmed their respectable biomimetic catecholase-like activity.
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