Optimization of a new activated carbon based sorbent for on-line preconcentration and trace determination of nickel in aquatic samples using mixed-level orthogonal array design

A mini-column was made by packing alpha-diphenylglyoxime (DPG), a known ligand for complexation with nickel ions, loaded on activated charcoal (AC). Water samples were buffered at the pH range 8-9 and then passed through the column. After the preconcentration step, the column was eluted with 0.2 M nitric acid into the atomic absorption spectrometer (AAS). Mixed-level orthogonal array design (OAD) was used as a chemometric approach to study the effect of various factors on recovery of extraction. Factors such as pH, amount of sorbent, flow rate of sample, concentration and volume of the sample were investigated. Effects of interference ions, i.e., Co, Cu, Bi, Fe(II), Pt and Pd was also studied. This method provides precise results (RSD < 5%) with a detection limits of 0.05 mu g l(-1).