Preparation and evaluation of a functionalized polymer-coated silica based sorbent for metal ion separation

A silica based sorbent with an anion complexone polymer coating, [24]ane-N-6 macrocycle, was prepared. The chelation properties of this material were investigated by elemental analysis, infrared spectra and Voige's method. The polymer-coated silica column (25-40 mu m, 100 x 4.6 mm i.d.) was employed for trace metal analyses. Oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid and acetic acid were used as mobile phases. Their retention characteristics were elucidated. Oxalic acid was found to be the most effective eluent. With a mobile phase consisting of oxalic acid (25 mM) and sodium nitrate (25 mM) at pH 4.2, the separation of copper(II), cadmium(II), cobalt(II) and zinc(II) in sea water could be achieved. The identification of metal ions was performed at 510 nm using 4(2-pyridylazo)resorcinol (1 x 10(-4) M) as post column reagent. The limits of detection were 5 x 10(-7) M, 1 x 10(-5) M, 3 x 10(-5) M and 2 x 10(-6) M for copper(II), cadmium(II), cobalt(II) and zinc(II) based on three times the standard deviation of the response for the lowest concentration (n = 5) in the chromatogram with a sample volume of 50 mu L. For evaluation of data reliability, oyster tissue (NIST SRM 1566a ) was studied with the proposed system.