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    Analysis of 226Ra, 232Th 40К and 137Cs in samples of soil from some areas of Republic of Macedonia by using gamma spectrometry
    (Mac Vet Rev, 2013-10-15)
    Todorovic Aleksandra
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    Stojanovska-Dimzoska Biljana
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    Validation of screening method for determination of methyltestosterone in fish
    (Mac Vet Rev, 2013-03-15)
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    Stojanovska-dimzoska biljana
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    Todorovic Aleksandra
    Anabolic androgenic steroids are synthetic derivatives of testosterone, which is the primary male sex hormone. These anabolic agents are used to increase the weight gain, to improve the food efficiency, storing proteins and to decrease fatness. However, depending on the use of anabolic agent in animal feed, anabolic residues that may occur in meat and meat products present risks to human health. The aim of this study was the validation of screening ELISA method for determination of methyltestoterone anabolic steroid in fish. The validation process was carried out according to Commission Decision 2002/657/EC criteria. The detection limit for methyltestosterone was 140.95 ng/kg and the detection capability was 564.43 ng/kg. The overall recoveries and the coefficients of variation (CV) were in the range of 82.4%-97.4% and 1.5%-6.9%, respectively, a working range between 50 to 4050 ng/kg, and the regression equation of the final inhibition curve was: y= -0,1741x + 1,5082, R2 = 0.9927. Because of the good recovery and precision, and satisfactory detection capability, this method is applicable in official control laboratories as a rapid screening method for determination of methyltestosterone in fish.
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    Determination of clenbuterol in meat samples with ELISA method
    (Faculty of Veterinary Medicine-Skopje, Ss. Cyril and Methodius University in Skopje, North Macedonia, 2011-09-11)
    Zehra Hajrulai-Musliu
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    Elizabeta Dimitrieska-Stojkovikj
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    Biljana Stojanovska-Dimzoska
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    Pavle Sekulovki
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    Multi-class/residue method for determination of veterinary drug residues, mycotoxins and pesticide in urine using LC-MS/MS technique
    (Springer Science and Business Media LLC, 2023-09-14)
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    Jovanov, Stefan
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    Musliu, Dea
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    Background Veterinary drugs are widely used in animals to prevent diseases and are a complex set of drugs with very different chemical properties. Multiclass and multi-residue methods for simultaneous detection of residues from veterinary drugs and contaminants in urine are very rare or non-existent. Therefore, the aim of this study was to develop and validate a sensitive and reliable quantitative LC-MS/MS method for simultaneous determination of a wide range of veterinary drug and pesticide residues and mycotoxins in bovine urine. This involved 42 veterinary drug residues (4 thyreostats, 6 anabolic hormones, 2 lactones, 10 beta agonists, 15 antibiotics, 5 sulphonamides), 28 pesticides and 2 mycotoxins. Stable isotopically labelled internal standards were used to facilitate effective quantification of the analytes. Analysis was performed in both positive and negative ionization modes with multiple reaction monitoring transitions over a period of 12 min. Results The parameters validated included linearity, limit of detection (LOD), limit of quantification (LOQ), detection capability (CCβ), decision limit (CCα), stability, accuracy and precision. The process followed guidelines of the regulation 2021/808/EC. The calibration curves were linear with coefficient of correlation (R2) from 0.991 to 0.999. The LODs were from 0.01 to 2.71 µg/L, while the LOQs were from 0.05 to 7.52 µg/L. The CCα and CCβ were in range 0.05–12.11 µg/L and 0.08–15.16 µg/L. In addition, the average recoveries of the spiked urine samples were from 71.0 to 117.0% and coefficient of variation (CV) < 21.38% (intraday and interday). Conclusion A new isotopic LC-MS/MS method has been developed, validated and applied for identification and quantification of 72 residues of veterinary drugs and pesticides and other contaminants such as mycotoxins in bovine urine. The most appropriated sample preparation procedures involved sodium acetate buffer, enzymatic hydrolysis using β-glucuronidase and cleanup solid phase extraction with OASIS SPE cartridges. The parameters were satisfactorily validated fulfilling requirements under Regulation 2021/808/EC. Consequently, the method could be used in routine analysis of bovine urine samples for simultaneous detection of veterinary drug and pesticide residues as well as contaminants such as mycotoxins.
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    Determination of Aflatoxins B1, B2, G1 and G2 in animal feeds with fluorimetric method
    (Српско ветеринарно друштво, Факултет за ветеринарна медицина, Србија, 2011-09-17)
    Zehra Hajrulai-Musliu
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    Elizabeta Dimitrieska-Stojkovikj
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    Biljana Stojanovska-Dimzoska
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    Pavle Sekulovki
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    Comparative analysis of conjugated linoleic acid content in cow, sheep and goat milk
    (Faculty of Food Technology Osijek (University of Osijek) and Faculty of Technology (University of Tuzla), 2019-10-24)
    Arapcheska, Mila
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    Tuteska, Jovanka
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    In recent years there has been increased interest in research on conjugated linoleic acid (CLA) and its potential health benefits: anticarcinogenic, antiatherogenic, antidiabetic and immunomodulatory effects. Term CLA describes a group of positional and geometric isomers of linoleic acid characterized by conjugated system of double bonds, separated by one single bond. The objective of this study was to analyze the differences in fatty acid (FA) profiles in cow, sheep and goat milk with an emphasis on the content of CLA. Milk samples were collected at conventional cow, sheep and goat farms, and according milk type were grouped in three groups. FA profiles were analyzed by gas chromatography. FAs were analyzed as methyl esters (FAMEs), and identified by comparison with methyl esters of standards. According to obtained results, significant difference (p<0.05) in CLA content was noted between three groups of samples, and also considerable individual variations in CLA content were noted inside each of group. Sheep milk samples were richer in CLA compared to goat and cow’s milk samples. Milk fat is the richest natural dietary source of CLA, and its content can be increased by manipulation of feeding regimes and genetic selection of dairy animals.
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    МУЛТИРЕЗИДУАЛНА АНАЛИЗА НА β-АГОНИСТИ ВО БИОЛОШКИ МАТРИКСИ СО ПРИМЕНА НА LC-MS/MS МЕТОД
    (2019-04-16)
    β-агонистите се синтетички произведени супстанци кои се користат во терапија на пулмонални обструктивни заболувања кај луѓето и домашните животни, а кај домашните животни исто така се користат и како срцеви тоници и токолитици. Покрај тоа β-агонистите може да се користат како промотори на раст кај многу животински видови за производство на месо. Апликацијата на 5-10 пати повисоки дози од одобрените терапевтски дози кај животните за производство на месо резултира со значително зголемување на мускулната маса, подобро искористување на храната, подобар состав на трупот и значително намалување на телесните масти. По употреба кај фармските животни, остатоци од β-агонистите се депонираат во ткивата и се потенцијален ризик по здравјето на луѓето. Постојат многу документирани случаи каде конзумирањето на месо и црн дроб кои содржат β-агонисти довеле до сериозни интоксикации кај луѓето. Поради тоа, со Директивата 96/22/ЕС, Европската Унија ја забранува употребата на β-агонисти кај фармски животни, додека со Директивата 96/23/ЕС, Европската Унија ги пропишува мерките за следење на овие супстанци во животните и производите од животинко потекло. Целта на ова истражување беше да се оптимизира и валидира потврден LC-MS/MS метод за определување на β-агонисти во урина, мускул и црн дроб и да се мониторира присуството на овие супстанци во наведените матрикси во периодот од 2014-2016 година. Со оптимизација на LC-MS/MS методот беа оптимизирани хроматографските услови и условите на масениот детектор. За секој β-агонист, со масениот детектор со користење на ESI+ јонизација, беа утврдени главните јони и по три продукт јони. Валидацијата на методот беше извршена според Одлуката на Комисијата 2002/657/EC и при тоа беа утврдени следните валидациски параметри: линеарност, CCα, CCβ, специфичност/селективност, точност и прецизност. Во истражувањето беа анализирани вкупно 525 примероци, од кои 274 урина, 150 мускул и 101 примерок црн дроб. Од добиените податоци од валидацијата може да се заклучи дека истите се во согласност со барањата од Одлуката на Комисијата 2002/657/EC. Според тоа во истражувањето е оптимизиран и валидиран линеарен, специфицичен, селективен, точен и прецизен потврден LC-MS/MS метод за определување на β-агонисти во урина, мускул и црн дроб кои потекнуваат од животни кои се користат во исхраната на луѓето. Во анализираните примероци не беа детектирани β-агонисти во концентрација над утврдената вредност за CCα, што практично значи дека резултатите укажуваат на нулта инциденца на нелегална или случајна употреба на β-агонисти и дека примероците се слободни од овие штетни супстанци.
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    Occurrence of Patulin In Apple-Based Juices And Concentrates
    (Faculty of Veterinary Medicine-Skopje, Ss. Cyril and Methodius University in Skopje, North Macedonia, 2013-09-08)
    Elizabeta Dimitrieska-Stojkovikj
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    Biljana Stojanovska Dimzoska
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    Gordana Ilievska
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    Aleksandra Todorovic
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    Radiation levels in samples of dicalcium phosphate (DCP) with a gamma spectrometry method.
    (UNIVERSITY OF EAST SARAJEVO FACULTY OF AGRICULTURE, Republic of Srpska, B&H et al, 2021-10-07)
    Angeleska, Aleksandra
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    Stojanovska-Dimzoska, Biljana