title: Determination of nickel in natural waters by FAAS after sorption on octadecyl silica membrane disks modified with a recently synthesized Schiff's base.
abstract: A simple, highly sensitive, accurate and selective method for the determination of trace amounts of Ni(2+) ions in water samples is proposed. The method is based on the separation and preconcentration of Ni(2+) on an octadecyl-bonded silica (ODBS) membrane disk modified by a recently synthesized Schiff's base N,N'-bis (3-methylsalicylidene) ortho phenylene diamine (MSOPD) at pH 7. The synthesis of this extractant ligand is also described. The retained nickel on the membrane was eluted with 2x5ml 0.5M HNO(3) and measured by flame atomic absorption spectrometry (FAAS) at 232.0nm. The extraction efficiency and the influence of the type and least amount of eluent for the stripping of Ni(2+) from the disks, pH, flow rates of sample solution and eluent, amount of MSOPD, effect of other ions, and breakthrough volume were evaluated. The maximum capacity of the membrane disks modified by 3mg of MSOPD was found to be 146+/-4mug Ni(2+). The 3sigma limit of detection of the method was 30ng per 1000ml and also an enrichment factor of 250 was obtained. The proposed method has been applied to the determination of nickel in several water samples with satisfactory results.
authors.affiliation: Department of Chemistry, Shahid Beheshti University, Tehran, Iran.
authors.forename: Afshin Rajabi
authors.initials: AR
authors.lastname: Khorrami
authors.forename: Hossein
authors.initials: H
authors.lastname: Naeimi
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Fakhari