ABSTRACT
New series of Co+2, Ni+2, Cu+2 and Zn+2 complexes have been synthesized using a bio-active hydrazone compound 4-hydroxybenzaldehyde-N-[5-chloro-2-oxo-1,2-dihydro-3H-indol-3-ylidene], abbreviated as [HL]. Complexes were characterized using elemental analysis, FT-IR, UV-visible spectroscopy conductivity and magnetic susceptibility measurements. Results showed that the bi-dentate [HL] coordinated in a square planner manner with Cu+2 while for the rest of the M+2 ions, it coordinated in a octahedral fashion. Free ligand and its metal complexes were also studied for their antioxidant potential by employing two methods i.e. DPPH radical scavenging and reducing power assay. It was observed that the metal complexes were considerably more potent free radical scavenger and had better reducing abilities compared to the free ligand, furthermore, for both in vitro assays, metal complexes turned out to be better DPPH scavengers and had better reducing abilities than the standards used during biological assays
ABSTRACT
The chlorination of water containing natural organic matter leads to the formation of disinfection by-products. Trihalomethanes [THM[s]] are the major category of disinfection by-product in chlorinated drinking water. This study aimed to investigate the presence of THM[s] in tap water samples collected from different localities of Karachi city. Liquid-liquid extraction and gas chromatography with an electron capture detector was used for the determination of THM[s]. The concentration of THM[s] in tap water samples of Karachi was found below the WHO guideline values. The mean concentration of chloroform, bromodichloromethane and dibromochloromethane were found as 30.40, 1.04 and 0.09 micro g L[-1] respectively. The relative standard deviations for these THM species were 1.15, 1.61 and 1.81 respectively. Bromoform [CHB[r3]] was not detected. On the basis of the results obtained by principal component analysis [PCA], CHCl[3] was found to be the most significant principal component. The effect of free chlorine residual and pH on the concentration of THM[s] were also assessed