Analytical Study on certain food tainting compounds

Abstract

It consists of 5 parts : Part I : Introduction : This part comprised a brief idea about food tainting , different sources of food tainting compounds , examples of chemicals causing taints and their possible origin . Part II: Litterature Review : This part was concerned with illustration of the different methods reported for the analysis of these compounds as taints in food matrices. Part III: Extraction and HPLC determination of food tainting compounds in different food matrices and Kinetic study of formation / uptake of these compounds. Section A: HPLC method for determination of Indole and 2,4- Dichlorophenol as food tainting compounds In this section, a validated, selective and sensitive HPLC method was proposed for the determination of indole and 2,4- dichlorophenol in their pure forms . Best separation was obtained using Agilent HC-C18 column (150 mm×4.6 mm, 5 μm) and the mobile phase was composed of water and methanol in the ratio of 35:65 , v/v, with a flow of 1 mL/min and diode array detection at wavelength 280 nm . The proposed method was found to be linear in the range ( 0.05 – 10.00 μg/mL ) and ( 0.50 – 40.00 μg/mL) of IND and DCP; respectively. The limit of detection of the method was found to be 0.01 and 0.16 μg/mL for IND and DCP ; respectively. Statistical comparison showed that there was no significant difference between the results obtained from the proposed method and the published ones . Summary xx Section B: Optimization and comparison of sample preparation methods for analysis of Indole and 2,4-Dichlorophenol as food tainting compounds This section included the development of new extraction methods of indole and 2,4-dichlorophenol from catfish samples , indole from potato samples and 2,4-dichlorophenol from fish farms water samples using solid - liquid extraction , ultrasonic assisted extraction , matrix solid phase dispersion and solid phase extraction methods . The parameters affecting solid-liquid extraction methods were studied and optimized . The optimum conditions were using ethyl acetate as extracting solvent at a liquid-to-solid ratio of 20: 1 , extraction time of 60 min and 90 min for catfish and potato samples ; respectively The parameters affecting ultrasonic assisted extraction methods were studied and optimized . The optimum conditions were : ultrasonic power of 700 W , sonication time of 20 and 30 min and extraction temperatures at 55 and 45 °C for catfish and potato samples; respectively. The parameters affecting matrix solid phase dispersion were studied and optimized. The optimum conditions were: diethyl ether as the eluting solvent at a ratio of 1:1 and 1:2 of sample matrix to sorbent support for catfish and potato samples; respectively. The parameters affecting solid phase extraction were studied and optimized. The optimum parameters were: methanol as eluting solvent and 3mL as optimum volume of eluting solvent . The procedures involving solid-liquid extraction, ultrasonic assisted extraction and matrix solid phase dispersion methods under optimum conditions were compared for catfish and potato samples fortified at different levels of IND and DCP. The highest recovery results were obtained using matrix solid phase dispersion in the range of (97. 88 – 99.68 % ) , (99.76- 100.58 %) and ( 98.41 – 99.66 %) for IND and DCP in catfish samples and for IND in potato samples ; respectively. Standard deviations ranged ( 0.56 – 1.24).Thus matrix solid phase dispersion was chosen as method of choice for extracting IND and DCP from catfish samples and for IND from potato samples ; respectively.