Determination of Tetracycline residues in red meat available in Oman

Tetracycline is heavily used in livestock production either for prophylaxis, treatment or as growth promoter. The residues of tetracycline in animal products have been investigated around the world and linked to imbalance in intestinal microflora, human allergic reactions, and other diseases. Researcher stated that the long term use of tetracycline as sub therapeutic dose increased level of antibiotic-resistant pathogens which is a global threat to human health and food security and development. Many studies reported that the tetracycline levels were above the maximum residual limit1,2. In Oman, few studies have been done using different techniques for investigating the antibiotics levels in animal products. Therefore, the aim of this study was to investigate the tetracycline residues in imported goat meat (liver and muscle) and to compare the levels of tetracycline residues between liver and muscles. A total of 48 fresh muscle and liver samples were taken from 24 Somali goats that were slaughtered at a slaughterhouse in Muscat. The extraction was done using the Agilent Enhanced Matrix Removal—Lipid (EMR—L) product. Four compounds were tested; Tetracycline, Oxytetracycline, Chlortetracycline and Doxycycline. The final extracts were analyzed using LC-MS/MS. The results showed no detection of tetracycline and doxycycline whereas, oxytetracycline and chlorotetracycline were found. 45% of muscle samples had OXY and CTC with concentration range of 6.04-6.23µg/kg and 5.48-8.35µg/kg, respectively. Around 42% of investigated liver samplesshowed OXY and CTC with concentration of 6.04-6.17 µg/Kg and 7.92-8.13µg/kg, respectively. In this study higher concentrations of OXY and CTC were detected in one muscle with values of 403.60035±234.8µg/kg and 274.8491±87.1058, respectively and one liver sample got higher concentration of OXY which was 3201.9±325.1µl/kg. These values were exceeding the MRL GSO 2481/2015, CX/MRL 2-2018 and EU 37/2010. These results might be related to withdrawal time as most of the samples had lower MRL. All samples were studied in triplicates to verify the results and using LCMSMS making data more satisfactory and validated.