Key words:Oreochromis niloticus, Mercury, lead, cadmium, Nile River Subjection to Heavy metals is an imperative normal issue coming to fruition because of various human exercises. The aim of this study was the assessment of some heavy metals and its possible hazards on fish and consumers. Eighty Nile tilapia fillet samples were collected from Nile canals and markets in Menoufia, Egypt for analysis of Mercury (Hg), lead (Pb), and cadmium (Cd), using atomic absorption flame. In general, wild tilapia samples contained higher mercury, lead and cadmium than those of farm tilapia samples. A positive correlation between heavy metals concentration and the fish size was observed, as the large sized tilapia samples had higher heavy metal residues than those of the small sized tilapia samples. Heavy metal levels in some fish samples in our investigations exceeded the maximum permissible limits of Egyptian standards.

Key words:Doxycycline, Oxytetracycilne, poultry meat, giblet.This study aims to detect the residues of Doxycycline, Oxytetracycline in broiler meat and giblet, using high performance liquid chromatography (HPLC), Doxycycline (DOC) residues were detected in 25%, 55 % and 70 % from the examined samples of meat, liver and kidney, respectively. Moreover, the levels of DOC residues (µg/kg) ranged from 3.4 to 15.9 µg/kg with a mean value 8.39 ± 0.14 µg/kg for meat,13.3 to 2753.5 µg/kg with a mean value 1142.85 ± 21.09 for liver and from 25.1 to 3661.6 µg/kg with a mean value 1305.59 ± 27.68 µg/kg for kidney. Oxytetracycline residues were detected in 25%, 60% and 45% of meat, liver and kidney, respectively. Moreover, the levels of oxytetracycline residues (µg/kg) ranged from 0.2 to 128.1 µg/kg with a mean value 37.52 ± 0.41 µg/kg for meat, 34.5 to 1248.0 µg/kg with a mean value 435.31 ± 12.86 µg/kg for liver and 26.8 to 412.7 µg/kg with a mean value 162.23 ± 5.35 µg/kg for kidney. Also this study revealed that frying is more efficient than boiling in decrease the residue limit of these two antibiotics.