Megersa, Negussie (PhD)Tolessa, Tesfaye2018-06-262023-11-092018-06-262023-11-092010-06http://etd.aau.edu.et/handle/12345678/3501A simple sample preparation technique using a hollow fiber membrane in conjunction with high performance liquid chromatography has been developed for the extraction and determination of s-triazine herbicides and their major metabolites from environmental water and human urine samples. Optimum extraction conditions have been evaluated with respect to solvent type, acceptor and sample pH, extraction time, shaking speed and salt content as well as humic acid effect. The extraction method has been validated for matrices such as reagent water, tap water, river water and human urine samples, indicating that regent water can be selected as representative matrix for routine analysis of these environmental water samples and human urine samples. A high level of detection linearity with regression coefficients (r2) ranged from 0.994 to 0.999 was obtained for herbicides over a range of analyte concentrations between 50 and 100 μg/L, using peak area as a response variable. The repeatability and reproducibility of the method were less than 11 and 17% for concentration of 50 μg/L, respectively. Limits of detection of the method ranged from 0.03 to 1.12 μg/L and the limits of quantification from 0.10 to 3.73 μg/L, which were low enough to determine all the herbicides residues except desisopropylatrazine at concentrations below or equal to the maximum residue levels (MRLs) specified by European Union. The method was finally applied to the determination of the herbicides in tap water, river water and human urine samples and the concentrations found in these samples were always lower than the MRLs except desisopropylatrazine in tap waterenFiber Supported Liquid Membrane ExtractionThesis