Quantitation of Oxytetracycline residue in three common cultured fishes of Bangladesh by analytical High Performance Liquid Chromatography (HPLC)

Abstract

Labeo rohita (Rui), Pangasius pangasius (Pangas) and Oreochromis niloticus (Tilapia) are popular in the Bangladesh because of reasonable e market prices and consumer demand. These fishes from five local markets (Dhanmondi, Mohammadpur, Shukrabad, Banani and Gazipur) were purchased randomly. The objective of this experiment was to do quantitation of oxytetracycline (OTC) residue in three common cultured fishes of Bangladesh by analytical High Performance Liquid Chromatography (HPLC). Oxytet racycline is one of two available FDA-approved antibiotics and regularly used in aquaculture farms of Bangladesh. This antibiotic was chosen for this experiment because it is excreted primarily unchanged through the urine and very minute amount gets deposits in fish muscle. It was necessary to find out whether this minute amount of antibiotic deposition in fish fulfills the requirement i.e. the range of oxytetracycline concentration in fish muscle according to regulatory body (FDA) should be within 55-83mg/Kg. Therefore, through this experiment fish extraction was done and oxytetracycline concentrations were determined by using High Performance Liquid Chromatography (HPLC). In this experiment, presence of residual of oxytetracycline in boiled fish is also included as a parameter to be observed. Two different fishes with confirmed oxytetracycline of two market areas were selected and individually each sample was boiled for 30 minutes. After boiling, the fish extraction process was carried once again and then finally the samples were run in HPLC. From the experiment it was found that concentration of oxytetracycline in Rui fish of Mohammadpur Townhall market, Shukrabad Kachabazar, Banani Kachabazar and Gazipur Kachabazar were 3237 mg/Kg, 1000 mg/Kg, 923.6 mg/Kg and 1287.5 mg/Kg resceptively. Similarly, Pangas fish of Dhanmondi (Meena bazar), Mohammadpur Townhall market, Shukrabad Kachabazar, Banani Kachabazar and Gazipur Kachabazar contained 1500 mg/Kg, 1061.8 mg/Kg, 1125 mg/Kg, 6250 mg/Kg, and 1675 mg/Kg of oxytetracycline respectively. Concentration of oxytetracycline in Tilapia fish of Mohammadpur Townhall market, Shukrabad Kachabazar, Banani Kachabazar and Gazipur Kachabazar were 874 mg/Kg, 1237.6 Mg/Kg, 9123.3 mg/Kg, 1625 mg/Kg respectively. Rui and Tilapia fish of Dhanmondi (Meena bazar) showed no trace of oxytetracycline. Finally results of the experiment revealed that residual of oxytetracycline in all three different fishes of different local market areas-Labeo rohita(Rui), Pangasius pangasius (Pangas) and Oreochromis niloticus (Tilapia) were within the range of 874-9123 mg/Kg- which is far too much in amount than the range being fixed by the regulatory body. It indicates whichever fish farms supplying Rui, Pangas and Tilapia in those five areas (Dhanmondi, Mohammadpur, Shukrabad, Banani and Gazipur) are using antibiotics at a very high concentration. Result of boiled fish states- two fish samples (Labeo rohita and Pangasius pangasius) had no trace of oxytetracycline after boiling. There is a possibility that during the boiling or cooking the oxytetracycline gets released from the fish and dissolves in the boiled water or in the fish gravy. Apart from this extreme concentrations level and the chronic presence of oxytetracycline inside the fish, sediments at the bottom of the pond should also be considered seriously because oxytetracycline excretes primarily unchanged through the waste materials of the fish. In spite of the potential risks related to the use of antibiotics and micro-organisms getting resistant to antibiotics, the concentrations found in the studied fishes are significantly higher than the regulatory body.