Markovski, Aleksandar

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Markovski, Aleksandar

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mraal3@yahoo.co.uk

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Investigation of Aril Characteristics of Some Autochthonous Pomegranate (Punica granatum L) Varieties in Macedonia
(National and University Library of the Republic of Srpska, 2017-12-18)
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Gjamovski, Viktor
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<jats:p>The individual aril characteristics of eight autochthonous pomegranate varieties (Lifanka, Bejnarija, Karamustafa, Ropkavac, Valandovska, LC, Zumnarija and Hicaz) from R. Macedonia were investigated using computer vision software methods. The great differences in the dimension of aril at the varieties were determined. The variety Lifanka is characterized with the greatest length (12.6 mm), width (9.5 mm) and mass (0.5 g) of the aril. Cross section aril area (61.1 mm2) and perimeter (31.6 mm) indicate that the variety ‘Hicaz’ is characterized with the smallest aril. Investigation of the aril shape showed different level of asymmetry depending on the variety. Generally, the variety Hicaz is characterized with the most asymmetrical aril. Based on CIELab system of coloration, great differences in the aril colour were noted among the investigated pomegranate varieties. The variety Hicaz had the darkest coloration (L* 19.3; a* 13.1; b* 5.3). High correlation dependence between coloration and shape and mass was determined.</jats:p>
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Investigation of the possibility for production of some stone fruit rootstocks by rooting cuttings
(Centre for Evaluation in Education and Science (CEON/CEES), 2015)
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Gjamovski, Viktor
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Application of High Performance Liquid Chromatography to the Analysis of Pesticide Residues in Apple Juice
(Walter de Gruyter GmbH, 2018-03-01)
Velkoska-Markovska, Lenche
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Petanovska-Ilievska, Biljana
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The modern apple production involves the use of large amounts of pesticides that can be found in processed products such as apple juice. Harmful effects of pesticide residues on humans, especially children, are well known, hence the content of pesticide residues in fruit, vegetables and their juices should be controlled. This study presents an application of a new, relatively simple and reliable analytical method for qualitative and quantitative determination of three organophosphorus and one organonitrogen pesticide residues in apple juices. The analysis utilizes reversed-phase high-performance liquid chromatography (RP-HPLC) followed by UV diode array detection. Prior to HPLC analysis, a solid-phase extraction (SPE) was used for analytes concentration and sample clean-up. Specificity, selectivity, linearity, precision, accuracy and limit of quantification (LOQ) were examined to assess the validity of the developed method. The method had satisfactory values of multiple correlation coefficients for calibration curves (R<jats:sup>2</jats:sup> ≥ 0.95 ). The precision was evaluated for the retention times and peak areas, and the estimated values for relative standard deviations (RSD) were 0.05 % - 0.18 % and 0.09 % - 0.62 %, respectively, which indicated an excellent precision of the proposed method. Under the established conditions, the recovery of analytes was 93.80 % - 119.41 %, with relative standard deviations below 0.56 %. This method was successfully applied for determination of some organophosphorus and organonitrogen pesticide residues in apple juices which were taken from Macedonian markets. The achieved values for LOQs were low enough compared to the MRLs of the investigated pesticides in apple according to the Regulation (EC) No 396/2005. Detectable residues of the examined pesticides were not found in the analyzed samples.</jats:p>
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APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY TO THE ANALYSIS OF PESTICIDE RESIDUES IN APPLE JUICE
(De Gruyter Open, 2018)
Velkoska-Markovska, Lenche
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Petanovska-Ilievska, Biljana
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The modern apple production involves the use of large amounts of pesticides that can be found in processed products such as apple juice. Harmful effects of pesticide residues on humans, especially children, are well known, hence the content of pesticide residues in fruit, vegetables and their juices should be controlled. This study presents an application of a new, relatively simple and reliable analytical method for qualitative and quantitative determination of three organophosphorus and one organonitrogen pesticide residues in apple juices. The analysis utilizes reversed-phase high-performance liquid chromatography (RP-HPLC) followed by UV diode array detection. Prior to HPLC analysis, a solid-phase extraction (SPE) was used for analytes concentration and sample clean-up. Specificity, selectivity, linearity, precision, accuracy and limit of quantification (LOQ) were examined to assess the validity of the developed method. The method had satisfactory values of multiple correlation coefficients for calibration curves (R2 ≥ 0.95). The precision was evaluated for the retention times and peak areas, and the estimated values for relative standard deviations (RSD) were 0.05 % - 0.18 % and 0.09 % - 0.62 %, respectively, which indicated an excellent precision of the proposed method. Under the established conditions, the recovery of analytes was 93.80 % - 119.41 %, with relative standard deviations below 0.56 %. This method was successfully applied for determination of some organophosphorus and organonitrogen pesticide residues in apple juices which were taken from Macedonian markets. The achieved values for LOQs were low enough compared to the MRLs of the investigated pesticides in apple according to the Regulation (EC) No 396/2005. Detectable residues of the examined pesticides were not found in the analyzed samples.
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DETERMINATION OF SOME PESTICIDE RESIDUES IN APPLE JUICE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
(University Ss. Cyril and Methodius in Skopje, 2019)
Velkoska-Markovska, Lenche
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Petanovska-Ilievska, Biljana
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A new, simple and reliable reversed-phase high-performance liquid chromatography (RP-HPLC) method for determination of 2,4-D ((2,4-dichlorophenoxy)acetic acid), atrazine, malathion, fenitrothion and parathion residues in apple juices has been developed and validated. Successful separation and quantitative determination of analytes were performed on Purospher STAR RP-8e (30 x 4 mm, 3 µm) analytical column, with mobile phase consisted of acetonitrile/water (45/55, V/V), flow rate of 1 mL/min, constant column temperature at 25 0C and UV detection at 220 nm and 270 nm. A solid-phase extraction (SPE) was used for concentration and clean-up of analytes. Specificity, selectivity, linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ) were tested for the method validation according to European Commission guidelines for pesticide residue analytical methods, and all performance characteristics were found within acceptance criteria. Calibration curves were linear within the range less than 50 % of the maximum residue limit (MRL) values and 20 % above for all investigated pesticides (R2 > 0.95). Under the stipulated conditions, values for relative standard deviations (RSD) of retention times and peak areas were 0.12 % - 0.28 % and 0.08 % - 8.50 %, respectively. The obtained values for recoveries ranged from 93.65 % - 118.62 %, with RSD ≤ 5.64 %. This method was successfully applied for determination of investigated pesticide residues in apple juice samples, which were taken from Macedonian markets. The run time of assay obtained from this chromatography condition was about 4 min.

Markovski, Aleksandar

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