New technique for detection and determination of malachite green residues in raw and heat treated fish / Mohamed Taha Elsayed Mohamed ; Supervised Salah Hussein Abou-Raya , Mohamed Emad Abdelaziz , Ali Ragab Shalaby

Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Food Science and Technology

The main aim of this study was to monitor malachite green (MG) residues in fish using new technique saving time and the cost of analysis. This can be used easily in markets and aquacultures as a qualitative method for MG detection in contaminated samples. Furthermore, the study aimed to developsimple, sensitive and economic quantitative method for MG determination in fish and to study the thermal stability of MG. The adsorbed MG on silica gel layer into the mini column was detected at visible light by naked eye without any tool or instrument. This method characterized by its ability to detect the minimum required performance limit (MRPL, 2 æg kg-1). Thin-layer chromatography (TLC) technique for MG determination was evaluated. The data showed that the correlation between the points of standard curve was higher than 0.989. The method characterized by its high sensitivity as it gave low values of regression factor for MG and LMG 3.86 and 3.24, respectively. The recovery of both MG and LMG in raw fish ranged from 62 and 78 % according to the contamination levels. Relative standard deviation was lower than 10 % in all cases which indicated to method accuracy, limit of detection (LOD) was 0.7 ng for MG. The corresponding value of limit of quantitation (LOQ) was 2 ng. A total of 100 fish samples (including 50 samples of fresh Tilapia Tilapia nilotic, and 50 samples of fresh mullet mogilev phallus) were randomly collected from different shops and retail markets at Cairo and Giza Governorates. Nine samples of tilapia fish and 7 samples of Mullet fish were contaminated with MG

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