Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Subject: search.filters.subject.Milk--Analysis

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  • Master Thesis
    The Confirmation of the Commercial Kits Used in the Detection of Antibiotics in Milk With Hplc (high Pressure Liquid Chromatography)
    (Izmir Institute of Technology, 2008) Alkan, Pınar; Tarı, Canan
    In this study, Charm II Assay was confirmed by HPLC for B-lactam, sulphonamide and tetracycline residues in milk. These antibiotics were chosen because they are most frequently used veterinary drugs and their detection have importance for milk quality and consumer's health. The results for confirmation of Charm II Assay showed that the test was very sensitive to all groups that were investigated and showed %100 true results for blank samples and spiked samples that were fortified with mixed standards at MRL (maximum residue limit) for each group. Average recoveries of HPLC used for confirmation were between 47% to 97% for beta-lactams, 61.5% to 84.8% for tetracyclines and 50.4% to 54.6% for sulphonamides. The results of analysis with the naturally contaminated milk samples showed that Charm II Assay may give false positive results. But this might be because of the high sensitivity of the test that sometimes HPLC may not reach that detection limit of Charm II assay or the milk samples may contain other compounds of investigated antibiotics that HPLC method can not detect.In samples that were collected for B-lactam determination, only 2 out of 81 samples were detected above MRL where the amounts were 6.5 ppb penicilin-G and 23.8 ppb ampicillin. The MRL for these B-lactam antibiotics are specified as 4 ppb by European Union regulations. The samples investigated for tetracycline residues which were found as positive and confirmed by HPLC were below MRL or negative. In samples investigated for sulphonamides only one sample out of 44 was above MRL where the amount was 119 ppb sulfamethazine.Analysis with 5 commercial milk samples showed none antibiotic residues. Only 4 samples out of 5 for sulphonamides were screened positive but after confirmation no residues were detected in these samples.
  • Master Thesis
    Investigation of the Pyhsical and Chemical Properties of Milk Containing Antibiotics
    (Izmir Institute of Technology, 2008) Yıldız, Özge; Ünlütürk, Sevcan; Ünlütürk, Sevcan
    This work aimed to find a basic and rapid screening method for antibiotic residues in UHT whole cow.s milk. For this purpose an investigation was conducted to screen some physical (e.g. acidity, pH, density, freezing point and electrical conductivity), thermo-physical (e.g. melting temperature, heat of fusion, evaporation temperature and heat of evaporation) and chemical properties (e.g. fat%, protein%, lactose%, minerals%, SNF%) of antibiotic free milk and milk fortified by Penicillin G, Ampicillin, Tetracycline. We can able determine whether residue of antibiotics making any difference on these selected properties. Thermo-physical properties were measured by differential scanning calorimeter (DSC), (TA Instruments, USA) and chemical properties were determined by using Lactostar (Funke Gerber Inc., Berlin, Germany).Antibiotic residues were detected by Copan Milk Test, Penzyme Test and ROSA Test and by high performance liquid chromatography (HPLC) method for confirmation of screening tests. Due to some drawbacks of screening tests, liquid chromatography was required for confirmation of antibiotic residues in milk. HPLC method showed that average recoveries of spiked Penicillin G at 2, 4, 8 ppb, spiked Ampicillin at 2, 4, 8 ppb and spiked Tetracycline at 100, 250, 500 ppb were ranged from 44.67% to 66.00%, from 62.50% to 87.52% and from 92.86% to 94.35%, respectively.We found that the acidity, pH and density of milk were independent of Penicillin G, Ampicillin and Tetracycline concentrations. Electrical conductivity (EC) were evaluated by applying ANOVA with Fisher.s test and Probabilistic neural network (PNN) method. ANOVA was also performed for DSC and Lactostar measurement results. This evaluation suggested that EC measurement can be a great promising technique for detection of antibiotic residues in milk, DSC is a good characterization tool for understanding of thermal events and the presence of antibiotic residues in milk influencing freezing point and minerals (EMC)%.