Analysis of residual levels of tetracyclines (TCs) in chicken meat was performed using a validated liquid chromatography coupled with a tandem mass spectrometry (LC-MS/MS) technique. Overall, the recoveries for TCs ranged from 56.9% to 101.2%, with standard deviations of 4.5-13.2%. Detection limits ranged from 7.9 to 14.6 µg kg⁻¹. In four of 60 samples, doxycycline (DXC) was determined in a range from 19.9 to 35.6 µg kg⁻¹; and in one sample tetracycline was detected at 17.2 µg kg⁻¹. Chlortetracycline (CTC) and oxytetracycline (OTC) were not detected in any of the tested samples. This study indicates that chicken meat sold in Bursa, Turkey, contained some residues of TCs. Therefore, stricter regulations for the use of antibiotics in the poultry industry and the monitoring of drug residues in chicken meat prior to marketing are needed. Finally, this method has been applied successfully for the confirmation of TCs in chicken meat.

The aim of this study was to determine the effects of boiling on nitrofuran 3-amino-2-oxazolidinone (AOZ) residues in eggs. The use of furazolidone in food-producing animals is banned within the EU and Turkey. The nitrofuran AOZ residues in raw and boiled eggs were analysed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in a chromotographic run of 20 min. The method validation was done according to the criteria laid down in Commission Decision No. 2002/657 EC. Linearity was proved between 0 to 1.5 µg/kg, decision limit (CCα) was 0.70 µg/kg, detection capability (CCβ) was 0.77 µg/kg, recovery values ranged between 88-97.9% and repeatability (CV) was 3-4.3%. The detected avarage nitrofuran AOZ residue level in 13 uncooked eggs by LC-MS/MS was 0.86±0.017 μg/kg which was increased to 2.42±0.037 µg/kg after boiling. In this study, it was surprisingly found that protein-bound side-chain metabolite, nitrofuran AOZ levels in eggs were significantly increased after boiling. This finding runs counter to the claim that heat process in general should decrease various antibiotic levels in food. The observed increase (P<0.001) in nitrofuran AOZ levels in boiled eggs relative to uncooked eggs may be due to enhanced efficiency of extraction in boiled samples. Therefore boiled eggs should be used for analysis of nitrofuran AOZ levels in order to obtain more reliable and more predictive results. Keywords: Nitrofuran AOZ, Residue, Egg, LC-MS/MS, Validation, Heat process Ticari Yumurtalarda Nitrofuran AOZ Kalıntıları Üzerine Kaynamanın Etkisi ÖzetBu çalışmanın amacı, yumurtalarda nitrofuran 3-amino-2-okzazolidinon (AOZ) kalıntıları üzerine kaynamanın etkisini belirlemektir. Furazolidonun gıda değeri taşıyan hayvanlarda kullanımı Avrupa Birliği'nde ve Türkiye'de yasaklanmıştır. Çiğ ve haşlanmış yumurtalarda nitrofuran AOZ kalıntıları sıvı kromatografi-tandem kütle spektrometrisi (LC-MS/MS) kullanılarak 20 dakikalık süre içerisinde analiz edilmiştir. Uygulanan yöntemin validasyonu Avrupa Birliği Komisyon Kararı No 2002/657 EC 'de belirtilen kriterlere göre yapıldı. Doğrusallık 0-1.5 µg/ kg, tayin limiti (CCα) 0.70 µg/kg, tayin kapasitesi (CCβ) 0.77 µg/kg, geri kazanım değerleri %88-97.9, tekrarlanabilirlik (CV) %3-4.3 arasında gerçekleşti. LC-MS/MS ile 13 adet çiğ yumurtada 0.86±0.017 µg/kg miktarında tespit edilen ortalama değer haşlama sonucu bakılan aynı yumurta örneklerinde istatistiki olarak önemli derecede artış göstererek 2.42±0.037 µg/kg ortalama değerlere yükselmiştir. Şaşırtıcı bir şekilde bu çalışmada, kaynamadan sonra yumurta içinde protein-bağlı yan-zincir metaboliti nitrofuran AOZ düzeylerinin arttığı tespit edildi. Bu bulgular genel olarak ısıl işlemin gıdalarda çeşitli antibiyotik düzeylerini azaltması gerektiği iddiası ile ters düşmektedir. Pişmemiş yumurtalara göre haşlanmış yumurtalarda nitrofuran AOZ düzeylerinde gözlenen artış (P<0.001) haşlanmış örneklerde ekstraksiyon etkinliğinin artmasına bağlı olabilir. Bu nedenle nitrofuran AOZ seviyelerinin analizinde daha güvenilir ve anlamlı sonuçlar eld...