Faculty of Agricultural Sciences and Food

Permanent URI for this communityhttps://repository.ukim.mk/handle/20.500.12188/2

Browse

Search Results

Now showing 1 - 10 of 11

Some of the metrics are blocked by your
consent settings
DETERMINATION OF PESTICIDE RESIDUES IN WATER BY LIQUID CHROMATOGRAPHY
(ECOLOGICAL MOVEMENT OF NOVI SAD, 2018)
Velkoska-Markovska, Lenche
;
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.
Some of the metrics are blocked by your
consent settings
APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY TO THE ANALYSIS OF PESTICIDE RESIDUES IN APPLE JUICE
(De Gruyter Open, 2018)
Velkoska-Markovska, Lenche
;
Petanovska-Ilievska, Biljana
;
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.
Some of the metrics are blocked by your
consent settings
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
;
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.
Some of the metrics are blocked by your
consent settings
DETERMINATION OF SOME PESTICIDE RESIDUES IN APPLE JUICE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
(University Ss. Cyril and Methodius in Skopje, 2019)
Velkoska-Markovska, Lenche
;
Petanovska-Ilievska, Biljana
;
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.
Some of the metrics are blocked by your
consent settings
DETERMINATION OF BISPHENOL A IN BEVERAGES BY RP-HPLC
(Biotechnical Faculty of the University of Montenegro, 2019)
Petanovska-Ilievska, Biljana
;
Jankulovska, S., Mirjana
;
Velkoska-Markovska, Lenche
;
Spasovska, Jasmina
Bisphenol A (BPA) is a monomer widely used in the production of polycarbonate, epoxy resins, diacrylates and phenolic resins. A small quantity of BPA can migrate into the food and thus it can be potential hazard for human health and environment. Therefore, quantitative determination of BPA is of a great importance. A fast, simple, precise and economic RP-HPLC method with UV-DAD detection for quantitative determination of BPA in beverages was developed. Three different analytical columns were tested: Hypersil ODS (250 mm x 4.6 mm; 5 µm), LiChrospher 60 RP-Select B (125 mm x 4 mm; 5 µm) and Purospher® STAR RP-18 endcapped (30 mm x 4 mm; 3 µm). Analyzed beverages were packed in plastic bottles and small glass bottles closed with a cops coated with epoxy resin on inside. For quantitative determination of BPA following experimental conditions were established: mobile phase consisted of acetonitrile/water 50/50 (v/v), flow rate of 1 mL/min, column temperature of 25 oС, injection volume of 5 µL and UV detection at 200 nm. The method was developed in an isocratic manner and with a reversed phase column. Prior the analyses the samples were filtrated through syringe filters Spartan – T with pore size 0.45 µm. The following parameters were determined: retention time, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, selectivity and sensitivity. The RP-HPLC method with UV-DAD detection can be successfully used for quantitative determination of BPA in non- alcoholic beverages without pre-treatment. The BPA was not detected in the analyzed beverages.
Some of the metrics are blocked by your
consent settings
RAPID RESOLUTION LIQUID CHROMATOGRAPHY METHOD FOR DETERMINATION OF CHLOROGENIC ACID IN ECHINACEA EXTRACTS
(University Ss. Cyril and Methodius in Skopje, 2018)
Velkoska-Markovska, Lenche
;
Petanovska-Ilievska, Biljana
;
Mihajlovski, Angel
This study presents a development and validation of a new, fast, efficient and cost effective reversed-phase rapid resolution liquid chromatography (RP-RRLC) method for determination of chlorogenic acid in echinacea extracts. The optimum separation with symmetrical peak shape and good index purity of the analyte was achieved on a Poroshell 120 EC-18 (50 mm x 3 mm; 2.7 µm) analytical column, mobile phase consisted of acetonitrile/(water with 1 % phosphoric acid), (10/90, V/V)in isocratic elution with flow rate of 1 mL/min and UV diode-array detection (UV-DAD) at 325 nm. The developed method was validated by testing specificity, selectivity, linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve of chlorogenic acid followed Beer’s law within the range 28.97 ng - 362.19 ng (R2 = 0.9994). The LOD was 0.29 pg, while LOQ was 0.96pg. The intra-day precisions was evaluated for the retention time, peak area and peak height and the calculated values for relative standard deviations (RSD) were 0.21 %, 0.11 % and 0.22 %, respectively. The mean recoveries ranged from 98.75 to 104.63 % and RSD was less than 0.23 %. The developed method was successfully applied for identification and quantification of chlorogenic acid in three samples of echinacea extracts, taken from local pharmacies.
Some of the metrics are blocked by your
consent settings
RP-HPLC-DAD method for simultaneous determination of desmedipham, phenmedipham and ethofumesate in a pesticide formulation
(Society of Chemists and Technologists of Macedonia, 2012-06-15)
Velkoska-Markovska, Lenče
;
Petanovska-Ilievska, Biljana
;
Vodeb, Lila
<jats:p>A fast, simple, precise and accurate reversed-phase high-performance liquid chromatography (RPHPLC)method with UV-DAD for simultaneous determination of desmedipham, phenmedipham and ethofumesate in the pesticide formulation “Inter OF” has been developed. The analysis was performed on a LiChrospher 60 RP-select B (25 cm × 0.4 cm, 5 μm, Merck) analytical column, with mobile phase of methanol/water (60/40, V/V), flow rate of 1 ml/min, UV-detection at 230 nm and constant column temperature at 25 ºC. The following parameters were determined for the developed method: retention factor, separation factor, limit of detection (LOD), limit of quantification (LOQ), precision of obtained results for peak area, linearity, recovery of analyte and active ingredients quantity in a pesticide formulation.</jats:p>
Some of the metrics are blocked by your
consent settings
Optimization and development of SPE-HPLC-DAD method for the determination of atrazine, malathion, fenitrothion and parathion pesticide residues in apple juice
(Society of Chemists and Technologists of Macedonia, 2013-12-01)
Velkoska-Markovska, Lenche
;
Petanovska-Ilievska, Biljana
<jats:p>ultraviolet–diode array detection (UV-DAD) for the simultaneous determination of atrazine, malathion, fenitrothion, and parathion residues in apple juices has been developed. For the enrichment and cleanup of compounds of interest, Supelclean ENVI-18 SPE tubes were used. Separation and quantitative determination of the analytes were performed on a LiChrospher 60 RP-select B (125 mm × 4 mm, 5 μm, Merck) analytical column, the mobile phase consisting of acetonitrile/water (55/45, V/V) in isocratic elution with the following set values: flow rate of 1 ml/min, constant column temperature at 25 oC, and UV detection at 220 nm and 270 nm. The gathered values of the investigated pesticides from the apple juice samples were in the range 94.2 %–117.2 %. </jats:p>
Some of the metrics are blocked by your
consent settings
Development of reverse-phase high-performance liquid chromatography method for simultaneous determination of sodium benzoate and potassium sorbate in beverages
(Akademiai Kiado Zrt., 2017-09)
Petanovska-Ilievska, Biljana
;
Velkoska-Markovska, Lenche
;
Jankulovska, Mirjana S.
Reverse-phase high-performance liquid chromatography (RP-HPLC) method for simultaneous determination of sodium benzoate and potassium sorbate in beverages was developed using high speed column. The simple and rapid reverse-phase method for quantitative determination of both preservatives was established on LiChroCART® Purospher STAR RP-18e (30 mm × 4 mm; 3 μm) column, mobile phase consisted of ace- tonitrile–phosphate buffer (pH = 3.5) in volume ratio of 8:92 (v/v), flow rate of 1 mL min−1, ultraviolet (UV) detection at 195 nm for sodium benzoate and 260 nm for potas- sium sorbate, and constant column temperature at 25 °C. Linearity, precision, accuracy, limit of quantification (LOQ), and limit of detection (LOD) were tested for method vali- dation. Linearity range for sodium benzoate was 6.04–200.27 mg L−1 (R2 = 0.999) while, for potassium benzoate (R2 = 0.999), 12.19–406.36 mg L−1. The RSD values ≤1.03% dem- onstrate excellent intra-day precision. LOD for sodium benzoate and potassium sorbate was 0.004 and 0.003 mg L−1, while LOQ was 0.012 and 0.009 mg L−1, respectively. This method was applied for quantitative determination of investigated preservatives in bev- erages which were taken from Macedonian markets.
Some of the metrics are blocked by your
consent settings
Application of High Performance Liquid Chromatography for Determination of Metalaxyl, Acetamiprid and Azoxystrobine in Tomato Samples
(Pleiades Publishing Ltd, 2019-04)
Mirjana S. Jankulovska, null
;
Velkoska-Markovska, Lenche
;
Petanovska-Ilievska, Biljana
;
Ilievski, Ugrin
A new rapid and simple method for simultaneous determination of azoxystrobin, acetamiprid and metalaxyl in tomatoes has been developed and validated. The separation and quantification of investigated pesticides was performed by reverse-phase HPLC with diode-array detection. Pesticide residues were extracted with acetone and purified by liquid‒liquid extraction and solid-phase extraction. The best results were obtained using acetonitrile‒water (50 : 50, v/v) as a mobile phase at a flow rate of 1 mL/min and UV detection at 220 and 250 nm. The optimal analytical separation was achieved with a LiChrospher 60 RP-select B (250 × 4 mm, 5 μm) column. The developed method was validated for linearity, sensitivity (limits of detection and quantification), accuracy (recovery) and intraday precision (repeatability). This method may find further application in analyses of tomato samples contaminated with residues of investigated pesticides.

Faculty of Agricultural Sciences and Food

Browse

Filters

Settings

Sort By

Results per page

Search Results