Faculty of Agricultural Sciences and Food

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Development and validation of an RP-HPLC method for the determination of caffeine and preservatives (sodium benzoate and potassium sorbate) in sports and energy drinks
(Springer Science and Business Media LLC, 2025-06-20)
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Stojchevska, Simona
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Development and validation of an RP-HPLC method for the determination of caffeine and preservatives (sodium benzoate and potassium sorbate) in sports and energy drinks
(Springer Science and Business Media LLC, 2025-06-20)
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Stojchevska, Simona
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Development and validation of RP-HPLC method for determination of some pesticide residues in apple samples
(Akademiai Kiado Zrt., 2024-12-23)
Velkoska-Markovska, Lenche
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Ilievski, Ugrin
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Jankulovska, Mirjana S.
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Petanovska-Ilievska, Biljana
Apples are among the most common fruits, produced on the territory of North Macedonia. Before they reach the market, it is essential to be tested for pesticide residues, which are used for protection against pests for this culture, and in order to ensure the customer safety. For this reason, a novel and simple method for simultaneous determination of captan, folpet, difenoconazole and chlorpyrifos in apple samples has been developed and validated. Acetone is used for extraction of the pesticide residues, followed by liquid-liquid (LLE) and solid–phase extraction (SPE). Separation and quantiﬁcation of analytes is achieved on reversed-phase high performance liquid chromatography (RP-HPLC) with UV diode array detector (UV-DAD). The best results are obtained using analytical column LiChrospher 60 RP-select B (250 mm 3 4 mm, 5 μm), with isocratic elution and acetonitrile/0.1 % acetic acid in water (70:30, V/V) as a mobile phase. The ﬂow rate is 1 mL min 1, and UV detection is performed at 220 and 230 nm. The linearity of the method is tested in the range of 1.50–3.60 mg kg 1 for captan and folpet, and 0.35 – 0.60 mg kg 1 for difenoconazole and chlorpyrifos. The obtained values for recovery and RSD ranged from 94.94 to 114.63 %, and 0.09–9.25 %, respectively. The validated method is successfully applied to apple samples for the determination of the investigated pesticide residues.
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Development and validation of RP-HPLC method with UV-DAD detection for simultaneous determination of acesulfame K, sodium saccharin and aspartame in beverages
(Akademiai Kiado Zrt., 2024-09-30)
Jankulovska, Mirjana S.
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Josimovska, Teodora
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Velkoska-Markovska, Lenche
Artificial sweeteners are low-calorie substances used as food additives with aim to impart a sweet taste to beverages without adding significant calories. Due to the regulatory compliance regarding the type and the amount of artificial sweetener, and due to the large consumption of beverages and the effects of artificial sweeteners on human health, their identification and quantification is of a great importance. In this research simultaneous determination of acesulfame K (ACE-K), sodium saccharin (Na-SAC) and aspartame (ASP) as the most commonly used sweeteners in beverages was performed with a reversed – phase high performance liquid chromatography (RP – HPLC) with diode array detection (DAD). The best separation of the analytes was achieved on a Poroshell 120 EC-C18 (3.0 3 50 mm, 2.7 μm) column and isocratic elution with a mobile phase consisted of acetonitrile and diluted phosphoric acid (pH 5 3.8) with 7/93 volume ratio (V/V), and ﬂow rate of 1 mL min 1. The chromatographic process was followed at 195, 220 and 230 nm, under constant column temperature (25 8C). Under these chromatographic conditions, the total time of analysis was less than 5 min. The developed method was validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantiﬁcation (LOQ). The LOD under established chromatographic conditions was 0.03, 0.07 and 0.17 mg L 1 for Na-SAC, ACE-K and ASP, respectively. The amount of artiﬁcial sweeteners in analyzed samples ranged from 30.32 to 148.37 mg L 1 for ACE-K, from 16.10 to 93.05 for Na-SAC, and from 6.06 to 512.72 for ASP. The validated method was successfully applied for determination of analytes in different commercially available beverages.
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Development and validation of RP-HPLC method with UV-DAD detection for simultaneous determination of acesulfame K, sodium saccharin and aspartame in beverages
(Akademiai Kiado Zrt., 2024-09-30)
Jankulovska, Mirjana S.
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Josimovska, Teodora
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Velkoska-Markovska, Lenche
<jats:title>Abstract</jats:title><jats:p>Artificial sweeteners are low-calorie substances used as food additives with aim to impart a sweet taste to beverages without adding significant calories. Due to the regulatory compliance regarding the type and the amount of artificial sweetener, and due to the large consumption of beverages and the effects of artificial sweeteners on human health, their identification and quantification is of a great importance. In this research simultaneous determination of acesulfame K (ACE-K), sodium saccharin (Na-SAC) and aspartame (ASP) as the most commonly used sweeteners in beverages was performed with a reversed – phase high performance liquid chromatography (RP – HPLC) with diode array detection (DAD). The best separation of the analytes was achieved on a Poroshell 120 EC-C18 (3.0 × 50 mm, 2.7 µm) column and isocratic elution with a mobile phase consisted of acetonitrile and diluted phosphoric acid (pH = 3.8) with 7/93 volume ratio (<jats:italic>V/V</jats:italic>), and flow rate of 1 mL min<jats:sup>−1</jats:sup>. The chromatographic process was followed at 195, 220 and 230 nm, under constant column temperature (25 °C). Under these chromatographic conditions, the total time of analysis was less than 5 min. The developed method was validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD under established chromatographic conditions was 0.03, 0.07 and 0.17 mg L<jats:sup>−1</jats:sup> for Na-SAC, ACE-K and ASP, respectively. The amount of artificial sweeteners in analyzed samples ranged from 30.32 to 148.37 mg L<jats:sup>−1</jats:sup> for ACE-K, from 16.10 to 93.05 for Na-SAC, and from 6.06 to 512.72 for ASP. The validated method was successfully applied for determination of analytes in different commercially available beverages.</jats:p>
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MARKET RESEARCH - HOW INTERESTED ARE CONSUMERS IN MEAT PRODUCTS WITH FEWER E-NUMBERS IN THEIR DECLARATION
(University Ss. Cyril and Methodius in Skopje, 2021)
Silovska Nikolova, Aleksandra
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Velkoska-Markovska, Lenche
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DETERMINATION OF PESTICIDE RESIDUES IN WATER BY LIQUID CHROMATOGRAPHY
(ECOLOGICAL MOVEMENT OF NOVI SAD, 2018)
Velkoska-Markovska, Lenche
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Petanovska-Ilievska, Biljana
This paper presents the application of a new, precise and accurate high-performance liquid chromatography (HPLC) method with ultraviolet-diode array detection (UV-DAD) for determination of some organophosphorus, phenoxycarboxylic acid and organonitrogen pesticide residues in water samples. The successful separation and quantitative determination of analytes were achieved using a LiChrospher 60 RP-Select B (125 x 4 mm, 5 µm) analytical column maintained at 25 °C and UV detection at 220 nm. The mixture of acetonitrile/water (55/45, V/V) was used as a mobile phase, with flow rate of 1 mL/min. The proposed method was successfully applied for the determination of investigated pesticides in water samples.
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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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DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR DETERMINATION OF SOME PESTICIDE RESIDUES IN WATER SAMPLES
(Macedonian Academy of Sciences and Arts, 2019)
Velkoska-Markovska, Lenche
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Petanovska-Ilievska, Biljana
The development of a new reversed-phase high-performance liquid chromatography method (RP-HPLC) with ultraviolet-diode array detection (UV-DAD) for simultaneous determination of 2,4-D, atrazine, malathion, fenitrothion and parathion residues in different water samples are described in this paper. The developed method has been validated according to European Commission guidelines for pesticide residue analytical methods, and all performance characteristics were found within acceptance criteria. The best separation and quantitative determination of the analytes were achieved using a LiChrospher 60 RP-select B (250 × 4 mm, 5 µm) analytical column, under the isocratic elution with mobile phase consisting of acetonitrile/water (60/40, V/V), flow rate of 1 ml/min, constant column temperature at 25 °C and UV-detection at 220 nm and 270 nm. The run time of analysis under the stipulated chromatographic conditions was about 10 min.
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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.

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